Forming a non-monocrystalline silicone semiconductor having pin junction including laminated intrinsic layers

ABSTRACT

A non-monocrystalline silicon semiconductor device having a pin junction is formed by forming a first doped semiconductor layer of a first conductivity disposed on a substrate. A first intrinsic layer is deposited on the first doped semiconductor layer employing RF energy. A second intrinsic layer is deposited on the first intrinsic layer employing microwave energy and RF energy simultaneously. A semiconductor precursor gas, including germanium and a semiconductor precursor gas including silicon are supplied to the second intrinsic layer during its formation. The content of the semiconductor precursor gas containing germanium is greater than the semiconductor gas including silicon in the layer thickness direction in the second intrinsic layer at a P-layer side. A second doped semiconductor layer is deposited on the second intrinsic layer.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a division of application Ser. No. 08/150,813, filedNov. 12, 1993, now U.S. Pat. No. 5,429,685.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photoelectric conversion elementcomposed of silicon non-single crystalline material, a fabricationmethod thereof, and a power generation system using the photoelectricconversion element.

Particularly, the invention relates to a photoelectric conversionelement wherein the bandgap of a pin-type photoelectric conversionsemiconductor is change, and a deposition method of said photoelectricconversion element by plasma CVD.

2. Related Background Art

In the prior art, various proposals have been made for a photoelectricconversion element of the pin-type structure composed of siliconnon-single crystalline material, in which an i-type layer containssilicon and germanium atoms, with the bandgap varying in the i-typelayer. For example, the following have been reported:

(1) "Optimum deposition conditions for a-(Si, Ge):H using atriode-configured rf glow discharge system," J. A. Bragagnolo, P.Littlefield, A. Mastrovito, and G. Storti, Conf. Rec. 19th IEEEPhotovoltaic Specialists Conference, 1987, pp. 878-883.

(2) "Efficiency improvement in amorphous-SiGe:H solar cells and itsapplication to tandem type solar cells," S. Yoshida, S. Yamanaka, M.Konagai, and K. Takahashi, Conf. Rec. 19th IEEE Photovoltaic SpecialistsConference, 1987, pp. 1101-1106.

(3) "Stability and terrestrial application of a-Si tandem type solarcells," A. Hiroe, H. Yamagishi, H. Nishio, M. Kondo, and Y. Tawada,Conf. Rec. 19th IEEE Photovoltaic Specialists Conference, 1987, pp.1111-1116.

(4) "Preparation of high quality a-SiGe:H films and its application tothe high efficiency triple-junction amorphous solar cells," K. Sato, K.Kawabata, S. Terazono, H. Sasaki, M. Deguchi, T. Itagaki, H. Morikawa,M. Aiga, and K. Fujikawa, Conf. Rec. 20th IEEE Photovoltaic SpecialistsConference, 1988, pp. 7378.

(5) U.S. Pat. No. 4,816,082

(6) U.S. Pat. No. 4,471,155

(7) U.S. Pat. No. 4,782,376

Also, several theoretical researches on the characteristics of aphotovoltaic element having a variable bandgap have been reported, forexample,

(8) "A novel design for amorphous silicon alloy solar cells," S. Guha,J. Yang, A. Pawlikiewicz, T. Glatfelter, R. Ross, and S. R. Ovshinsky,Conf. Rec. 20th IEEE Photovoltaic Specialists Conference, 1988, pp.79-84.

(9) "Numerical modeling of multijunction, amorphous silicon based P-I-Nsolar cells," A. H. Pawlikiewicz and S. Guha, Conf. Rec. 20th IEEEPhotovoltaic Specialists Conference, 1988, pp. 251-255.

Such photovoltaic elements in the prior arts have a varying bandgaplayer inserted into p/i and n/i interfaces for preventing recombinationof photoexcited carriers in the vicinity of the interfaces, increasingopen-circuit voltage, and enhancing carrier range of holes.

SUMMARY OF THE INVENTION

Conventional photovoltaic elements containing silicon and germaniumatoms and having a variable bandgap are required to have higherperformance, e.g., in the photoelectric conversion efficiency, andreliability in practical use, however, a further improvement is desiredin the open-circuit voltage and the diffusion length of holes bysuppressing the recombination of photoexcited carriers.

Also, in conventional photovoltaic elements the photoelectric conversionefficiency may decrease when the illuminating light applied to thephotovoltaic elements is weak.

Further, in conventional photovoltaic elements, photoelectric conversionefficiency may decrease if they are annealed due to distortion in thei-type layer.

An object of the present invention is to provide a photoelectricconversion element which can solve the above conventional problems.

That is, it is an object of the present invention to provide aphotoelectric conversion element in which the open-circuit voltage andthe diffusion length of holes are improved by preventing therecombination of photoexcited carriers.

It is another object of the present invention to provide a photoelectricconversion element with improved conversion efficiency when theilluminating light applied to the photoelectric conversion element isweak.

Further, it is another object of the present invention to provide aphotoelectric conversion element which has a smaller decrease in thephotoelectric conversion efficiency when annealed for a long time.

In addition, it is another object of the present invention to provide aphotoelectric conversion element which has a smaller change inphotoelectric conversion efficiency as a result of temperaturevariations.

Further, it is another object of the present invention to provide asystem utilizing a photoelectric conversion element in which theaforementioned objects have been achieved.

The present invention has been achieved as a result of careful researchto solve the conventional problems and to accomplish the above objects.It provides a photovoltaic element in which at least a p-type layer, ani-type layer, and an n-type layer made of silicon non-single crystallinesemiconductor material are laminated. The i-type layer is of a laminatedstructure consisting of an i-type layer formed by microwave plasma CVDlocated on the side of the n-type layer and an i-type layer formed by RFplasma CVD located on the side of the p-type layer. The i-type layerformed by microwave plasma CVD is formed such that the minimum value ofbandgap is positioned toward the p-type layer side displaced from thecentral position of the i-type layer by a microwave plasma CVD processin which a lower microwave energy and a higher RF energy than themicrowave energy necessary to decompose 100% of the source gas aresimultaneously applied to a source gas composed at least of a siliconatom-containing gas and a germanium atom-containing gas at a pressure of50 mTorr or less. The i-type layer formed by RF plasma CVD is formed 30nm thick or less at a deposition rate of 2 nm/sec or less by an RFplasma CVD process using a source gas at least containing a siliconatom-containing gas.

A photovoltaic element of the present invention in desirable form ischaracterized by a valence electron control agent serving as an electrondonor and a valence electron control agent serving as an electronacceptor simultaneously doped into the i-type layer formed by microwaveplasma CVD and/or the i-type layer formed by RF plasma CVD. Thesevalence electron control agents are a Group III and/or Group V elementof the periodic table, and preferably are distributed in the i-typelayer by microwave plasma CVD.

A photovoltaic element of the present invention in desirable form ischaracterized by the maximum value of the bandgap positioned in thep-type layer side and/or the n-type layer side within the i-type layerformed by microwave plasma CVD. The region of the maximum value ofbandgap is from 1 to 30 nm.

Further, oxygen and/or nitrogen atoms are contained in the i-type layerformed by microwave plasma CVD and/or the i-type layer formed by RFplasma CVD.

Also, it is characterized by the content of hydrogen contained in thei-type layer formed by microwave plasma CVD changing corresponding tothe content of silicon atoms.

Further, a photovoltaic element of the present invention in desirableform is one in which the p-type layer and/or the n-type layer is of alaminated structure consisting of a layer having a Group III or Group Velement of the periodic table as the main constituent and a layercontaining a valence electron control agent and having silicon atoms asthe main constituent. In particular, the layer having a Group III and/orGroup V element of the periodic table as the main constituent isdesirably 1 nm thick or less.

A power generation system of the present invention comprises aphotovoltaic element, an accumulator for accumulating electric powersupplied from the photovoltaic element and/or supplying electric powerto an external load, and a control system for controlling the electricpower to be supplied from the photovoltaic element to the accumulatorand/or the external load while monitoring the voltage and/or current ofthe photovoltaic element.

A photovoltaic element of the present invention in which at least ap-type layer, an i-type layer, and an n-type layer made of siliconnon-single crystalline semiconductor material are laminated ischaracterized in that the i-type layer is of a laminated structureconsisting of an i-type layer formed by microwave plasma CVD located onthe side of the p-type layer and an i-type layer formed by RF plasma CVDlocated on the side of the n-type layer. The i-type layer is formed bymicrowave plasma CVD such that the minimum value of bandgap is displacedtoward the p-type layer side away from the central position of thei-type layer by a microwave plasma CVD process in which a lowermicrowave energy and a higher RF energy than the microwave energynecessary to decompose 100% of the source gas are simultaneously appliedto a source gas composed at least of a silicon atom-containing gas and agermanium atom-containing gas at a pressure of 50 mTorr or less. Thei-type layer formed by RF plasma CVD is 30 nm, thick or less at adeposition rate of 2 nm/sec or less.

A photovoltaic element of the present invention in desirable form ischaracterized by a valence electron control agent as an electron donorand a valence electron control agent as an electron acceptorsimultaneously doped into the i-type layer formed by microwave plasmaCVD and/or the i-type layer formed by RF plasma CVD. These valenceelectron control agents are a Group III or Group V element of theperiodic table, and preferably are distributed in the i-type layer bymicrowave plasma CVD.

Also, a photovoltaic element of the present invention in desirable formis characterized by the maximum value of the bandgap located in thep-type layer side and/or the n-type layer side within the i-type layerformed by microwave plasma CVD. The region of the maximum value ofbandgap is from 1 to 30 nm.

Further, oxygen and/or nitrogen atoms are contained in the i-type layerformed by microwave plasma CVD and/or the i-type layer formed by RFplasma CVD.

Also, it is characterized by the content of hydrogen contained in thei-type layer formed by microwave plasma CVD which changes correspondingto the content of silicon atoms.

A power generation system of the present invention comprises aphotovoltaic element, an accumulator for accumulating electric powersupplied from the photovoltaic element and/or supplying electric powerto an external load, and a control system for controlling the electricpower to be supplied from the photovoltaic element to the accumulatorand/or the external load while monitoring the voltage and/or current ofthe photovoltaic element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a typical view of the layer structure of a photovoltaicelement according to the present invention.

FIG. 2 is a typical band diagram of the photovoltaic element accordingto the present invention in the thermal equilibrium state.

FIG. 3 is a typical view of another layer structure of a photovoltaicelement according to the present invention.

FIGS. 4-17 are typical band diagrams for explaining other bandgapvariations of the photovoltaic elements according to the presentinvention.

FIG. 18 is a schematic view of a manufacturing apparatus relying on themicrowave plasma CVD method for fabricating the photovoltaic elementaccording to the present invention.

FIG. 19 is a schematic view of a manufacturing apparatus relying on theRF plasma CVD method for fabricating the photovoltaic element accordingto the present invention.

FIGS. 20-22 are schematic views of manufacturing apparatuses of theseparated, multi-chamber deposition type for fabricating photovoltaicelements according to the present invention.

FIGS. 23A and 23B are graphical representations showing the patterns ofthe flow rates of SiH₄ and GeH₄ gases varying with time.

FIG. 24 is a graphical representation showing the variation of thei-type layer bandgap in the layer thickness direction.

FIGS. 25A and 25B are graphical representations showing a SiH₄ gas flowrate pattern during forming of the i-type layer, and the variation inlayer thickness direction of Si and H atoms in the i-type layer.

FIG. 26 is a graphical representation showing variation of SiH₄ and GeH₄gas flow rate patterns with time.

FIGS. 27-32 are typical circuit diagrams of power supply systemsaccording to the present invention.

FIGS. 33A and 33B are graphical representations respectively showing theflow rate of NO/He gas introduced during forming of the i-type layer,varying with time, and the variation in the layer thickness direction ofN and O atoms in the i-type layer.

FIGS. 34-40 are graphical representations showing the patterns ofvariation of the flow rates of SiH₄ and GeH₄ gases with time.

FIGS. 41 and 42 are graphical representations showing variation of theflow rates of BF₃ /H₂ and PH₃ /H₂ gases introduced during forming of thei-type layer.

FIGS. 43 and 44 are graphical representations showing the variation inthe layer thickness direction of the contents of B and P atoms in thei-type layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The methods and configurations of the present invention will now bedescribed with reference to the drawings.

FIG. 1 is a typical view of the structure of a photovoltaic elementaccording to the present invention, wherein incident light is indicatedby 107. The photovoltaic element is comprised of conductive substrate101 having a light reflecting layer and a light reflection multiplyinglayer, n-type silicon non-single crystalline semiconductor layer 102,non-single crystalline semiconductor layer 103 substantially of i-typeformed by microwave plasma CVD and containing silicon and germaniumatoms, i-type layer 108 formed by RF plasma CVD, p-type siliconnon-single crystalline semiconductor layer 104, transparent electrode105, and collector electrode 106.

FIG. 2 is a typical band diagram of the photovoltaic element having alayer structure as shown in FIG. 1, in a state of thermal equilibrium,which is an example of the photovoltaic element of the presentinvention. In FIG. 2, E_(F) represents the Fermi level, E_(C) theconduction band, and E_(V) the valence band. This figure shows thejoining of an n-type silicon non-single crystalline semiconductor layer212, a non-single crystalline semiconductor layer 213 substantially ofi-type formed by microwave plasma CVD and containing silicon andgermanium atoms, an i-type layer 215 formed by RF plasma CVD, and ap-type silicon non-single crystalline semiconductor layer 214. Since theminimum value of bandgap takes place at a position shifted toward thep-type layer 214 side in the i-type layer 213 by microwave plasma CVDand there is a larger conduction band electric field on the p-type layerside in the i-type layer 213, the efficient separation of electrons andholes results, whereby the recombination of electrons and positive holesin the vicinity of the interface between the p-type layer and i-typelayer can be reduced. Also, since the electric field of the valence bandincreases from the i-type layer 213 toward the n-type layer, therecombination of electrons and holes photoexcited in the vicinity of thei-type layer 213 and the n-type layer 212 can be reduced.

Further, by adding a valence electron control agent as an electron donorand a valence electron control agent as an electron acceptorsimultaneously into the i-type layer formed by microwave plasma CVD, thediffusion length of electrons and holes can be extended. In particular,by containing a relatively great amount of valence electron controlagent in the region where the bandgap is minimum, the diffusion lengthof electrons and holes can be effectively extended. As a result, thehigh electric field in the vicinity of the interface between the n-typelayer and the i-type layer formed by microwave plasma CVD can be furthereffectively utilized, so that the collection efficiency of electrons andholes photoexcited in the i-type layer can be significantly enhanced.Since the defect levels (so-called D₋, D₊) can be compensated by thevalence electron agent in the vicinity of the interface between then-type layer and the i-type layer, the dark current (in reverse bias)decreases due to hopping conduction via the defect level. In particular,if more valence electron control agent is contained in the vicinity ofthe interface than inside the i-type layer, internal stress such asdistortion caused by rapid change of the constituents peculiar to thevicinity of the interface can be decreased, so that the defect level inthe vicinity of the interface can be lowered. Therefore, theopen-circuit voltage and fill factor of the photovoltaic element can beimproved.

In addition, by simultaneously adding a valence control agent as theelectron donor and a valence electron agent as the electron acceptorinto the i-type layer formed by microwave plasma CVD, the resistance tooptical degradation can be increased. The exact mechanism is unknown,but may be considered as follows. That is, it is generally believed thatthe characteristics of a photovoltaic element may be degraded due torecombination centers of carriers with dangling bonds produced byillumination. In the present invention, both the valence electron agentas the electron donor and the valence electron agent as the electronacceptor are contained within the i-type layer and are not 100%activated. As a result, if dangling bonds were produced by lightillumination, they would react with inactive valence electron controlagent to compensate the dangling bonds.

Also, particularly when the intensity of light illuminating thephotovoltaic element is weak, the probability of trapping photoexcitedelectrons and holes will decrease because the defect level iscompensated by the valence electron control agent. A sufficientelectromotive force can be produced because the dark current in reversebias is small, as previously described. As a result, even when theintensity of light illuminating the photovoltaic element is weak,excellent photoelectric conversion efficiency can be exhibited.

In addition, the photovoltaic element according to the present inventionis less likely to suffer a decrease in photoelectric conversionefficiency even when annealed for a long time. The exact mechanism isunknown, but may be considered as follows. That is, a photovoltaicelement is formed by changing the constituents to provide a continuouschange of the bandgap. Hence, a distortion is produced inside thephotovoltaic element. That is, this results in a number of weak bondswithin the photovoltaic element. Owing to vibrations, the weak bondswithin the i-type non-single crystalline semiconductor may be severed toform dangling bonds. However, it is believed that because of the addingof a valence electron control agent serving as an electron donor and avalence electron control agent serving as an electron acceptorsimultaneously, the photovoltaic element has an increased localflexibility to prevent the photoelectric conversion efficiency of thephotovoltaic element from decreasing even with annealing for a longtime. Besides, since inactive donor or acceptor atoms are primarilythree-coordinated, the local flexibility may also increase. As a result,the photoelectric conversion efficiency is less liable to decreaseduring annealing for a long time. However, since inactive donor oracceptor atoms form defects, they must be limited below a certainamount. That is, the preferable amount of inactive donor or acceptoratoms is from 0.1 to 100 ppm.

By providing an i-type layer 215 formed by RF plasma CVD and having athickness of 30 nm or less between the p-type layer 214 and the i-typelayer 213 at a deposition rate of 2 nm/sec or less, the photoelectricconversion efficiency of the photovoltaic element can be furtherimproved. In particular, the photovoltaic element of the presentinvention is less likely to change in photoelectric conversionefficiency when used in an environment where temperature varies greatly.

The non-single crystalline semiconductor layer of the i-type layerdeposited by RF plasma CVD can be deposited at low power at a depositionrate of 2 nm/sec or less because vapor phase reaction hardly occurs. Asa result, the packing density of the deposited film is higher, and whenthe i-type layer is laminated on the film deposited by microwave plasmaCVD, the amount of interface levels between the i-type layers becomeslower. In particular, when the deposition rate of the film deposited bymicrowave plasma CVD is 5 nm/sec or greater, the surface level is veryhigh because the surface of the i-type layer is not sufficiently relaxedafter the microwave plasma is stopped. By forming a film by microwaveplasma CVD at a slow deposition rate on the surface of such i-typelayer, the surface level of the film deposited by microwave plasma CVDmay possibly be reduced by the annealing due to diffusion of hydrogenatoms which occurs at the same time as formation of the film depositedby RF plasma CVD.

Also, by containing more valence electron control agent in the vicinityof the interface between the p-type layer and the i-type layer formed byRF plasma CVD than inside the i-type layer, internal stress such asdistortion caused by rapid change of constituents peculiar to thevicinity of the interface can be decreased, and consequently the defectlevel in the interface vicinity can be decreased. Therefore, theopen-circuit voltage and fill factor of the photovoltaic element can beimproved.

In addition, by simultaneously adding a valence electron control agentserving as an electron donor and a valence electron control agentserving as an acceptor within the i-type layer formed by RF plasma CVD,resistance to optical degradation can be increased. The exact mechanismis unknown, but may be considered as follows. That is, it is generallybelieved that the characteristics of a photovoltaic element may bedegraded due to recombination of carriers with dangling bonds producedby light illumination. In the present invention, both the valenceelectron control agent serving as the electron donor and the valenceelectron control agent serving as the acceptor are contained within thei-type layer and are not 100% activated. As a result, if dangling bondswere produced by light illumination, they would react with the inactivevalence control agent to compensate for dangling bonds.

Also, particularly when the intensity of light directed to thephotovoltaic element is weak, the probability of trapping ofphotoexcited electrons and holes will decrease because the defect levelsare compensated by the valence control agent. Sufficient electromotiveforce can be produced because the dark current in reverse bias is small,as previously described. As a result, when the intensity of lightilluminating the photovoltaic element is weak, excellent photoelectricconversion efficiency can be exhibited.

In addition, the photovoltaic element has a photoelectric conversionefficiency which hardly decreases even when annealed for a long time.The exact mechanism is unknown, but may be considered as follows. Thatis, it is believed that if a valence electron control agent serving asan electron donor and a valence electron control agent serving as anacceptor are added simultaneously in the vicinity of the interfacebetween the p-type layer and the i-type layer composed of very differentconstituents, the photovoltaic element has an increased localflexibility which prevents the photoelectric conversion efficiency fromdecreasing even during annealing for a long time.

The p-type layer of the photovoltaic element according to the presentinvention has a laminated structure consisting of a layer containing aGroup III element of the periodic table as the main constituent(hereinafter referred to as a doping A layer) and a layer having siliconatoms as the main constituent and containing a valence electron controlagent (hereinafter referred to as a doping B layer), whereby the lighttransmittance of the p-type layer can be increased and the specificresistance of the p-type layer reduced. In particular, the contact sideof the p-type layer and the i-type layer is preferably a layercontaining the valence electron control agent and having silicon atomsas the main constituent (doping layer B). This makes it possible todecrease defects between the i-type layer and the p-type layer. Thelayer thickness of doping layer A is preferably in the range from 0.01to 1 nm. Also, the amount of hydrogen contained in doping layer A ispreferably 5% or less. Further, the amount of valence electron controlagent contained in doping layer B is preferably in the range from 1500to 10,000 ppm. The p-type layer has been thus described, but the n-typelayer can be also formed to the same effect by making a similarlaminated structure using a Group V element of the periodic table.

FIG. 5 is a typical diagram for explaining an example of the bandgapvariation of the photovoltaic element of the present invention.(Hereinafter, the bandgap variation within the i-type layer isrepresented with reference to 1/2 the bandgap (E_(g) /2), unlessotherwise specified, and the n-type layer (not shown) side is located tothe right and the p-type layer (not shown) side to the left in thefigure.) The example of FIG. 5 has an i-type layer formed by microwaveplasma CVD on the p-type layer side, wherein the minimum value of thebandgap is shifted closer to the p-type layer side within the i-typelayer formed by microwave plasma CVD, and the maximum value of bandgapoccurs both on the p-type layer side and the n-type layer side.

FIG. 6 is a typical explanatory diagram for the bandgap variation, drawnsimilar to FIG. 5. In FIG. 6, as in FIG. 5, an i-type layer formed by RFplasma CVD is provided on the p-type layer side, wherein the minimumvalue of bandgap is shifted closer to the p-type layer within the i-typelayer formed by microwave plasma CVD, and the maximum value of thebandgap is on the p-type layer side.

FIGS. 7 to 9 are examples of photovoltaic elements wherein an i-typelayer formed by RF plasma CVD is provided on the p-type layer side, withthe bandgap of the microwave plasma CVD layer decreasing monotonicallyuntil the i-type layer formed by microwave plasma CVD contacts thei-type layer formed by RF plasma CVD.

FIG. 7 shows an example comprising an i-type layer 312 formed by RFplasma CVD having a fixed bandgap on the p-type layer side, and ani-type layer 311 formed by microwave plasma CVD having its bandgapdecreasing from the n-type layer side to the i-type layer 312. Theminimum value of the bandgap occurs at the interface between the i-typelayer 312 and the i-type layer 311. The band junction between the i-typelayer 311 and the i-type layer 312 is discontinuous. In this way, byproviding a region of fixed bandgap, the dark current due to hoppingconduction via the defect levels in reverse bias of the photovoltaicelement can be suppressed to a minimum. As a result, the open-circuitvoltage of the photovoltaic element is increased.

The layer thickness of i-type layer 312 with the fixed bandgap is a veryimportant factor, and preferably is in the range from 1 to 30 nm. Whenthe layer thickness of the region with the fixed bandgap is below 1 nm,the dark current due to hopping conduction via the defect levels cannotbe suppressed, so that a higher open-circuit voltage of the photovoltaicelement cannot be expected. On the other hand, when the layer thicknessof the i-type layer with the fixed bandgap is above 30 nm, photoexcitedholes are likely to accumulate in the interface vicinity between thei-type layer with the fixed bandgap and the i-type layer having varyingbandgap, resulting in decreased collection efficiency of photoexcitedcarriers. That is, the short-circuit photocurrent decreases.

FIG. 8 is an example in which an i-type layer 322 formed by RF plasmaCVD and having a fixed bandgap is provided on the p-type layer side. Ani-type layer 321 formed by microwave plasma CVD has a varying bandgap,which on the n-type layer side is equal to that of the i-type layer 322.

FIG. 9 is an example comprising an i-type layer 332 formed by RF plasmaCVD and having a fixed bandgap provided on the p-type layer side, ani-type layer 331 formed by microwave plasma CVD and having its bandgapdecreasing monotonically from the n-type layer side to the p-type layerside, and an i-type layer 333 having a fixed bandgap formed by microwaveplasma CVD or by RF plasma CVD on the n-type layer side. The minimumvalue of bandgap occurs at the interface between the i-type layer 332and the i-type layer 331. The band junction between the i-type layer 332and the i-type layer 331 is discontinuous. In this way, by providing aregion of fixed bandgap between the p-type layer and the i-type layer331 and between the n-type layer and the i-type layer 331, the darkcurrent due to hopping conduction via the defect levels in reverse biasof the photovoltaic element can be suppressed to the minimum. As aresult, the open-circuit voltage of the photovoltaic element isincreased.

FIGS. 10 to 13 are examples in which the minimum value of bandgap occurswithin the i-type layer formed by microwave plasma CVD.

FIG. 10 is an example in which the photoconductive layer of aphotovoltaic element comprises an i-type layer 342 formed by RF plasmaCVD having a fixed bandgap provided on the p-type layer side, an i-typelayer 341 formed by microwave plasma CVD having the minimum value ofbandgap inside thereof, and an i-type layer 343 having a constantbandgap formed by microwave plasma CVD or by RF plasma CVD continuouslyjoined with the i-type layer 341. Because the bandgap variation iscontinuous, electrons and holes photoexcited in the varying bandgapregion of the i-type layer can be efficiently collected in the n-typelayer and the p-type layer, respectively. In particular, when the fixedbandgap regions 342, 343 are as thin as 5 nm or less, the dark currentwhen a reverse bias is applied to the photovoltaic element is decreasedin the region of the i-type layer having the greatly changing bandgap,and therefore the open-circuit voltage of the photovoltaic element isincreased.

FIG. 11 is an example of a photoconductive layer in which an i-typelayer 351 formed by microwave plasma CVD having a varying bandgap isjoined discontinuously, but relatively moderately, with an i-type layer352 formed by RF plasma CVD having a constant bandgap and an i-typelayer 353 having a constant bandgap formed by microwave plasma CVD or byRF plasma CVD. However, since the fixed bandgap region and the varyingbandgap region are moderately connected in the direction where thebandgap is widening, photoexcited carriers in the varying bandgap regionare efficiently injected into the fixed bandgap region. As a result, thecollection efficiency of photoexcited carriers increases.

Whether to connect the fixed bandgap region and the varying bandgapregion continuously or not will depend on the layer thicknesses of thefixed bandgap region and the abruptly varying bandgap region. When thefixed bandgap region is as thin as 5 nm or less and the rapidly varyingbandgap region is 10 nm or less in layer thickness, higher photoelectricconversion efficiency of the photovoltaic element can be obtained if thefixed bandgap region and the varying bandgap region are continuouslyconnected. On the other hand, when the fixed bandgap region is as thinas 5 nm or greater and the rapidly varying bandgap region is from 10 to30 nm in layer thickness, higher photoelectric conversion efficiency ofthe photovoltaic element can be obtained if the fixed bandgap region andthe varying bandgap region are discontinuously connected.

FIG. 12 is an example comprising an i-type layer 362 formed by RF plasmaCVD on the p-type layer side and an i-type layer 361 formed by microwaveplasma CVD having the minimum value of bandgap, in which the fixedbandgap region and the varying bandgap region are connected at twosteps. The minimum value of bandgap is displaced to the p-type layerside. Photoexcited carriers in the varying bandgap region can beefficiently collected so as to connect with a wider, fixed bandgapregion through moderately widening the bandgap from a minimum bandgapposition and rapidly widening the bandgap. Also, in FIG. 12, a regionwhere the bandgap rapidly increases toward the n-type layer is providedwithin the i-type layer in the vicinity of the n-type layer.

FIG. 13 is an example comprising an i-type layer 373 formed by RF plasmaCVD on the p-type side, an i-type layer 372 formed by microwave plasmaCVD having a fixed bandgap, an i-type layer 371 formed by microwaveplasma CVD which presents a region having the minimum value of bandgapinside thereof, and an i-type layer 374 formed by microwave plasma CVDor by RF plasma CVD in which a fixed bandgap region is provided withinthe i-type layer on either the p-type layer side or the n-type layerside. The fixed bandgap region on the p-type layer side is connectedthrough two steps of varying the bandgap through the varying bandgapregion, and connecting the bandgap region on the n-type layer sidethrough a rapid bandgap change.

As described above, by connecting the fixed bandgap region and thevarying bandgap region through similar constituents, internal distortioncan be decreased. As a result, there is less possibility of causing weakbonds within the i-type layer to be severed when annealed for a longtime, thereby increasing the defect level and decreasing thephotoelectric conversion efficiency, so that the high photoelectricconversion efficiency can be maintained.

Also, by containing a valence electron control agent in the i-typelayer, as previously described, the diffusion length of carriers withinthe i-type layer can be extended, and therefore the collectionefficiency of carriers can be increased. In particular, by changing theamount of valence electron control agent in accordance with thevariation of bandgap such that a greater amount is added in the narrowerbandgap region and a smaller amount in the wider bandgap region, thecollection efficiency of photoexcited carriers can be further increased.By containing more valence electron control agent on the p-type layerside and the n-type layer side within the i-type layer having a fixedbandgap than the region having the minimum bandgap, the recombination ofphotoexcited carriers can be prevented from occurring in the vicinity ofthe p/i interface and the n/i interface, so that the photoelectricconversion efficiency of the photovoltaic element can be improved.

FIG. 3 is a typical explanatory view showing another example of aphotovoltaic element according to the present invention, wherein theincident light is indicated by 3107. The photovoltaic element of thepresent invention is comprised of a conductive substrate 3101 having alight reflecting layer and a light reflection multiplying layer, ann-type silicon non-single crystalline semiconductor layer 3102, ani-type layer 3109 formed by RF plasma CVD, a non-single crystallinesemiconductor layer 3103 of substantially i-type formed by microwaveplasma CVD and containing silicon and germanium atoms, an i-type layer3108 formed by RF plasma CVD, a p-type silicon non-single crystallinesemiconductor layer 3104, a transparent electrode 3105, and a collectorelectrode 3106.

By inserting an i-type layer formed by RF plasma CVD 30 nm thick or lessbetween the n-type layer and the i-type layer formed by microwave plasmaCVD at a deposition rate of 2 nm/sec or less, the photoelectricconversion efficiency of the photovoltaic element can be furtherenhanced. In particular, the photovoltaic element of the presentinvention is less likely to change in photoelectric conversionefficiency when used in an environment of great temperature variations.

The microwave plasma CVD involves a greater kinetic energy of ions inthe deposition as compared with the RF plasma CVD, and may possiblycause damage to the lower semiconductor layer. Accordingly, it isrequired that the lower semiconductor layer be resistant to ion damage,and that the film deposited by microwave plasma CVD be of as goodquality as the underlying semiconductor and made under conditions whichcause less damage to the lower semiconductor layer. The depositionconditions of the photovoltaic element of the present inventionaccomplish this object.

Consequently, it is possible to form a photovoltaic element having areduced number of interface states at the interface between the n-typelayer and the i-type layer formed by RF plasma CVD, which results inimproved open-circuit voltage and short-circuited current of thephotovoltaic element.

FIG. 4 is a typical explanatory diagram showing an example of thebandgap variation of the photovoltaic element of FIG. 3. In an exampleof a FIG. 4 embodiment, the minimum value of the bandgap is near thep-type layer, and the maximum value of the bandgap is at the contactwith the p-type layer or the n-type layer. The i-type layer 4211 and thei-type layer 4212 are deposited by microwave plasma CVD, and i-typelayer 4213 is a non-single crystalline silicon layer deposited by RFplasma CVD. The i-type layer 4211 and the i-type 4213 are made to have asubstantially equal bandgap by adjusting the content of hydrogen.

FIG. 14 is a typical explanatory diagram of another bandgap variation,similar to FIG. 4. In FIG. 14, as in FIG. 4, the minimum value ofbandgap is closer to the p-type layer, but the maximum value of bandgapis in contact with the p-type layer. i-type layer 14221 and i-type layer14222 are deposited by microwave plasma CVD, and i-type layer 14223 is anon-single crystalline silicon layer deposited by RF plasma CVD. Thebandgap of the i-type layer 14221 and of the i-type layer 14223 arediscontinuous. With the bandgap configuration of FIG. 14 particularly,the open-circuit voltage can be increased.

FIGS. 9 to 11, FIG. 13, and FIGS. 15 to 17 are typical explanatorydiagrams showing the bandgap variations of photovoltaic elements inwhich a non-single crystalline layer of substantially i-type is providedbetween the n-type layer and the i-type layer by microwave plasma CVDand between the p-type layer and the i-type layer by RF plasma CVD.

In FIG. 9, the layer thickness of i-type layer 333 formed by RF plasmaCVD is a very important factor, and preferably is in the range from 1 to30 nm. When the layer thickness of the i-type layer with the fixedbandgap is below 1 nm, the dark current due to hopping conduction viathe defect levels cannot be suppressed, so that the higher open-circuitvoltage of the photovoltaic element cannot be expected. On the otherhand, when the layer thickness of the i-type layer 333 is above 30 nm,photoexcited holes are likely to accumulate in the vicinity of theinterface between the i-type layer 332 and the i-type layer 331 having avarying bandgap, resulting in decreased collection efficiency ofphotoexcited carriers. Consequently, the short-circuit photocurrentdecreases.

FIG. 15 is an example in which an i-type layer 15322 having a fixedbandgap formed by RF plasma CVD is provided between the p-type layer andan i-type layer 15321 formed by microwave CVD. An i-type layer 15323formed by RF plasma CVD having a bandgap equal to that of the i-typelayer 15321 is provided between the n-type layer and i-type layer 15321.

FIG. 16 is an example in which i-type layers 16332, 16333 formed by RFplasma CVD are provided between the p-type layer and the i-type layer16331 formed by microwave plasma CVD and between the n-type layer andthe i-type layer 16331. When a reverse bias is applied to thephotovoltaic element, the dark current is further decreased, resultingin increased open-circuit voltage of the photovoltaic element.

FIGS. 10, 11, 13, and 17 are examples of photovoltaic elements in whichthe i-type layer having fixed bandgap and formed by RF plasma CVD isprovided between the p-type layer and the i-type layer formed bymicrowave plasma CVD and between the n-type layer and the i-type layerformed by microwave plasma CVD. The rapidly varying bandgap region isprovided on the p-type layer side or n-type layer side of the i-typelayer formed by microwave plasma CVD.

FIG. 17 is an example in which the i-type layers 17362, 17363 with fixedbandgap and an i-type layer 17361 with varying bandgap are connectedthrough two steps, and in which the minimum bandgap position is closerto the p-type layer side. Photoexcited carriers in the varying bandgapregion can be efficiently collected by connecting the i-type layers17362, 17363 having wider fixed bandgap with the i-type layer 17361through two steps of moderately widening the bandgap from the minimumbandgap position and rapidly widening the bandgap therefrom. Also, inFIG. 17, the i-type layer 17361 is provided with a rapidly varyingbandgap toward the i-type layer 17363.

In the present invention, the minimum value of bandgap in the i-typelayer containing silicon and germanium atoms is preferably from 1.1 to1.6 eV, depending on the spectrum of illuminating light.

In the photovoltaic element with continuously varying bandgap accordingto the present invention, the inclination of the tail states in thevalence band is an important factor governing the characteristics of thephotovoltaic element, in which it preferably is smoothly continuous fromthe inclination of the tail states at the minimum value of bandgap tothe inclination at the maximum value of bandgap.

Thus, photovoltaic elements of a pin structure have been described, butthe above discussion can also apply to a photovoltaic element havinglaminated pin structures such as a pinpin or pinpinpin structure.

FIG. 18 is an explanatory diagram of a typical film forming apparatussuitable for carrying out a film forming method of the photovoltaicelements according to the present invention. The apparatus is comprisedof deposition chamber 1001, dielectric window 1002, gas introducing tube1003, substrate 1004, heater 1005, vacuum gauge 1006, conductance valve1007, auxiliary valve 1008, leak valve 1009, waveguide 1010, bias powersource 1011, bias rod 1012, shutter 1013, source gas supply unit 1020,mass flow controllers 1021 to 1029, gas inlet valves 1031 to 1039,source gas cylinder valves 1051 to 1059, pressure regulators 1061 to1069 and source gas cylinders 1071 to 1079.

The detailed deposition mechanism of the preferred deposition method ofthe photovoltaic element according to the present invention has not beenclarified, but may be considered as in the following.

It is believed that the active species suitable for forming a depositedfilm can be selected in such a manner as to apply to a source gas alower microwave energy than the microwave energy required to decompose100% of the source gas and simultaneously apply a higher RF energy tothe source gas. Further, it is believed that the mean free path ofactive species suitable for forming a high-quality deposited film islong enough in the state where the internal pressure of the depositionchamber during decomposition of the source gas is 50 mTorr or less, andtherefore the vapor phase reaction can be suppressed to a minimum. It isbelieved that in the state where the internal pressure of the depositionchamber is 50 mTorr or less, the RF energy controls the potentialbetween the plasma and the substrate within the deposition chamberpractically without any effect on the decomposition of source gas. Thatis, with the microwave plasma CVD method, the potential between theplasma and the substrate is small, but the potential (+ at the plasmaside and - at the substrate side) between the plasma and the substratecan be increased by inputting the RF energy together with the microwaveenergy. In this way, it is believed that if the plasma potential ispositive or higher than the substrate active species decomposed bymicrowave energy deposited on the substrate, at the same time +ionsaccelerated by the plasma potential will impinge onto the substrate topromote a relaxation reaction on the surface and provide ahigher-quality deposited film. In particular, this is remarkable whenthe deposition rate is several nm/sec or greater.

Further, since the RF frequency is high, unlike DC, the potentialbetween the plasma and the substrate can be determined from thedistribution of dissociated ions and electrons. That is, the potentialbetween the substrate and the plasma can be determined by synergisticaction of ions and electrons. Accordingly, there is the effect that lesssparking will occur within the deposition chamber. As a result, a stableglow discharge can be maintained for a long time, e.g. over 10 hours.

In addition, since the flow rate and flow ratio of source gas may changewith time or spatially while depositing the layer with a varyingbandgap, the DC voltage must be changed appropriately with time orspatially, in the case of DC. However, in the deposited film formingmethod of the present invention, the percentage of ions may change dueto changes in the flow rate and flow ratio of source gas occurring withtime or spatially. In correspondence thereto, the RF self-bias isautomatically changed. As a result, when RF is applied to the bias rodto change the flow rate and flow ratio of source gas, the discharge canbe quite stable as compared with the DC bias method.

In the deposited film forming method, to obtain a desired bandgapvariation, it is preferable to mix a silicon atom-containing gas and agermanium atom-containing gas at a distance 5 m or less away from thedeposition chamber. If those source gases are mixed over 5 m apart, adelay in the mixing of source gases or a mutual diffusion of sourcegases may occur even by controlling mass flow controllers correspondingto the desired bandgap variation, because the mixing position of thesource gases is away from the deposition chamber, resulting in a driftfrom the desired bandgap. That is, if the mixing position of the sourcegases is too far away from the deposition chamber, the controllabilityof the bandgap may decrease.

Furthermore, to change the content of hydrogen contained in the i-typelayer in a direction of layer thickness, it is necessary that the RFenergy to be applied to the bias rod be increased when the content ofhydrogen is desired to be greater, while the RF energy applied to thebias rod is decreased when the content of hydrogen is desired to besmaller. On the other hand, when the DC energy is applied together withthe RF energy, a large positive DC voltage may be applied to the biasrod, if the content of hydrogen atoms is desired to be greater, while asmall positive DC voltage may be applied to the bias rod if the contentof hydrogen atoms is desired to be smaller.

The photovoltaic element of the present invention is formed with adeposited film, for example, in the following manner. First, a substrate1004 for the formation of the deposited film is mounted within adeposition cheer 1001 as shown in FIG. 18, and the deposition chamber issufficiently exhausted of air to 10⁻⁵ Torr or less. A turbo molecularpump is suitable for this purpose, but an oil diffusion pump may also beused. In the case of the oil diffusion pump, a gas such as H₂, He, Ar,Ne, Kr, Xe should be introduced into the deposition chamber if theinternal pressure of the deposition chamber 1001 falls below 10⁻⁴ Torrto prevent the oil from diffusing back to the deposition chamber. Afterthe deposition chamber is sufficiently exhausted, the gas such as H₂,He, Ar, Ne, Kr, Xe is introduced into the deposition chamber so that thedeposition chamber may reach an internal pressure substantially equal tothat when the source gas for the formation of the deposited film isflowed. The optimal range of pressure within the deposition chamber isfrom 0.5 to 50 mTorr. If the internal pressure within the depositionchamber is stabilized, a substrate heater 1005 is turned on to heat thesubstrate from 100° to 500° C. If the temperature of the substrate isstabilized at a predetermined value, the flow of gas is stopped and thesource gas for the formation of the deposited film is introduced in apredetermined quantity from the gas cylinder via the mass flowcontrollers into the deposition chamber.

The supply of the source gas for the formation of deposited film to beintroduced into the deposition chamber may be determined depending onthe deposition conditions within the deposition chamber. On the otherhand, the internal pressure within the deposition chamber whenintroducing the source gas is very important, the optimal internalpressure within the deposition chamber being from 0.5 to 50 mTorr.

Also, in the deposited film forming method of the photovoltaic elementaccording to the present invention, the microwave energy to be inputinto the deposition chamber is important. The microwave energy may beappropriately determined by the flow rate of source gas introduced intothe deposition chamber, but must be smaller than the microwave energynecessary to decompose 100% of the source gas, the preferred range beingfrom 0.02 to 1 W/cm³. The preferred frequency range of microwave energyis from 0.5 to 10 GHz. In particular, the frequencies near 2.45 GHz aresuitable. Also, in order to reproducibly form the deposited film by thefilm forming method and form the film over a few to several tens ofhours, the stability of the frequency of microwave energy is veryimportant. The frequency variation preferably should fall within therange of ±2%. Further, the ripple of the microwaves is preferably withinthe range of ±2%. Further, the RF energy input into the depositionchamber together with the microwave energy is very important, thepreferable range of the RF energy being from 0.04 to 2 W/cm³.

The preferable frequency range of the RF energy is from 1 to 100 MHz. Inparticular, 13.56 MHz is optimal. Also, the variation in the RFfrequency is within ±2%, and the waveform is preferably smooth.

When the RF energy is supplied, the RF energy may be appropriatelyselected by the area ratio between the area of the bias rod for thesupply of the RF energy and the grounded area, and in particular, whenthe area of the bias rod for the supply of the RF energy is narrowerthan the grounded area, the self-bias (DC component) for the supply ofthe RF energy on the power supply side should be grounded. Further, whenthe self-bias (DC component) for the supply of the RF energy on thepower supply side is not grounded, the area of the bias rod for thesupply of the RF energy is preferably larger than the grounded area withwhich the plasma makes contact.

Such microwave energy is introduced from the waveguide 1010 via thedielectric window 1002 into the deposition chamber, and concurrently theRF energy is introduced from the bias power supply 1011 via the bias rod1012 into the deposition chamber. In such a state, the source gases aredecomposed for a desired time to form a deposited film having a desiredlayer thickness on the substrate. Thereafter, the input of the microwaveenergy and the RF energy is stopped, the deposition chamber is exhaustedof air, and then purged with a gas such as H₂, He, Ar, Ne, Kr or Xe,whereafter a deposited non-single crystalline semiconductor film istaken out from the deposition chamber.

In addition to the RF energy, DC voltage may be applied to the bias rod1012. The DC voltage preferably has such a polarity that the bias rod ispositive. The preferable range of the DC voltage is from 10 to 300 V.

FIG. 19 is a typical explanatory diagram of a deposited film formingapparatus suitable for the deposition of an i-type layer by an RF plasmaCVD method for making a photovoltaic element according to the presentinvention. The apparatus is comprised of deposition chamber 1101,cathode 1102, gas introducing tube 1103, substrate 1104, heater 1105,vacuum gauge 1106, conductance valve 1107, auxiliary valve 1108, leakvalve 1109, RF power supply 1111, RF matching box 1112, source gassupply unit 1020, mass flow controllers 1021 to 1029, gas inlet valves1031 to 1039, source gas cylinder valves 1051 to 1059, pressureregulators 1061 to 1069, and source gas cylinders 1071 to 1079.

The i-type layer formed by RF plasma CVD of the photovoltaic elementaccording to the present invention can be formed, for example, in thefollowing manner.

First, a substrate on which the i-type layer formed by microwave plasmaCVD has been deposited is mounted as the substrate 1104 on the heaterwithin the deposition chamber 1101. The door is closed, and thedeposition chamber 1101 is exhausted below 10⁻³ Torr. A substrateheating gas such as H₂, He, Ar, Ne, Kr or Xe is flowed at the same flowrate and under the same pressure as when conducting the RF plasma CVD.At the same time, the substrate heater 1105 is turned on, and is set ata desired substrate temperature. If the temperature is stabilized at apredetermined value, the flow of the substrate heating gas is stopped,and a predetermined amount of source gas for the formation of depositedfilm is introduced from the gas cylinders via mass flow controllers intothe deposition chamber 1101.

If the internal pressure of the deposition chamber is stabilized at adesired pressure by the source gas, a desired RF energy is introducedfrom the RF power supply via the matching box 1112 to the cathodeelectrode 1102. A plasma is then excited and deposition is sustained fora predetermined time. After deposition for the predetermined time, thesupply of RF energy is stopped, the substrate heater is turned off, thesupply of source gas is stopped, and the deposition chamber issufficiently purged. If the substrate temperature falls below roomtemperature, the substrate is taken out from the deposition chamber.

When the i-type layer is deposited by RF plasma CVD, optimal conditionsare: the substrate temperature is from 100° to 350° C., the internalpressure is from 0.1 to 10 Torr, the RF power is from 0.01 to 5.0 W/cm²,and the deposition rate is from 0.01 to 2 nm/sec.

A more preferable deposition apparatus for the photovoltaic element ofthe present invention successively combines microwave plasma CVDapparatuses and RF plasma CVD apparatuses, as shown in FIGS. 20, 21, and22. The deposition chamber for microwave plasma CVD and the depositionchamber for RF plasma CVD are preferably separated by a gate. The gateis preferably a mechanical gate valve or gas gate.

In the film forming method as described above, suitable source gases forthe deposition of silicon include SiH₄, Si₂ H₆, SiF₄, SiFH₃, SiF₂ H₂,SiF₃ H, SiF₃ H₈, SiD₄, SiHD₃, SiH₂ D₂, SiH₃ D, SiFD₃, SiF₂ D₂, SiD₃ H,and Si₂ D₃ H₃.

Suitable sources gases for the deposition of germanium include GeH₄,GeD₄, GeF₄, GeFH₃, GeF₂ H₂, GeF₃ H, GeHD₃, GeH₂ D₂, GeH₃ D, Ge₂ H₆, andGe₂ D₆.

In the present invention, valence electron control agents to beintroduced into the non-single crystalline semiconductor for the controlof the valence electrons of the non-single crystalline semiconductorlayer may include Group III or Group V atoms.

In the present invention, starting materials used for the introductionof Group III atoms include boron hydrides such as B₂ H₆, B₄ H₁₀, B₅ H₉,B₅ H₁₁, B₆ H₁₀, B₆ H₁₂, and B₆ H₁₄, and boron halides such as BF₃ andBCl₃, for the introduction of boron atoms. Besides these, AlCl₃, GaCl₃,InCl₃, and TlCl₃ may be included.

In the present invention, the starting materials used for theintroduction of Group V atoms include phosphorus hydrides such as PH₃and P₃ H₄, and phosphorus halides such as PH₄ I, PF₃, PF₅, PCl₃, PCl₅,PBr₃, PBr₅, and PI₃, for the introduction of phosphorus atoms. Besidesthese, AsH₃, AsF₃, AsCl₃, AsBr₃, AsF₅, SbH₃, SbF₃, SbF₅, SbCl₃, SbCl₅,BiH₃, BiCl₃, and BiBr₃ may also be included.

The amount of Group III or Group V atoms introduced into the i-typelayer of the non-single crystalline semiconductor layer to accomplishthe objects of the present invention are preferably in the range of 1000ppm or less. It is preferable to add the Group III or Group V atomssimultaneously to compensate.

Also, the gasifiable compounds as cited above may be introduced into thedeposition cheer by diluting them with a gas such as H₂, D₂, He, Ne, Ar,Xe, or Kr. The optimal gases are H₂ and He.

Examples of nitrogen-containing gases include N₃, NH₃, ND₃, NO, NO₃, andN₂ O.

Examples of oxygen-containing gases include O₂, CO, CO₂, NO, NO₂, N₂ O,CH₃ CH₂ OH, and CH₃ OH.

The p-type layer and the n-type layer having a laminated structurecomposed of a layer containing a Group III and/or Group V element as themain constituent (doping layer A) and a layer containing a valenceelectron control agent and having silicon atoms as the main constituent(doping layer B) can be formed using a deposited film forming apparatusrelying on the microwave CVD or RF plasma CVD.

Doping layer A is preferably deposited using a gas containing a GroupIII and/or Group V element as the source gas and by microwave CVD or RFplasma CVD. In particular, in order to reduce the content of hydrogen indoping layer A, it is preferred that the source gas is decomposed at ashigh a power as is possible.

Doping layer B is preferably deposited using a gas containing a GroupIII and/or Group V element as the valence electron control agent whichis mixed with a silicon atom-containing gas and by microwave CVD or RFplasma CVD.

On the other hand, if a doping layer B containing a crystalline phase isdeposited by microwave CVD, it is preferable that the RF energy issmaller than the microwave energy and the microwave energy is relativelylarge. The preferable microwave energy is from 0.1 to 1.5 W/cm³. To makethe crystal grain diameter larger, hydrogen dilution is preferable. Therate of dilution of source gas by a hydrogen-containing gas ispreferably from 0.01 to 10%.

Also, when the doping layer B containing crystal phase is deposited byRF plasma CVD, the silicon atom-containing gas is diluted with hydrogengas (H₂, D₂) to a concentration from 0.01 to 10%, and the RF power ispreferably from 1 to 10 W/cm².

When the p-type layer and/or the n-type layer of the photovoltaicelement of the present invention constitutes a lamination of dopinglayer A and doping layer B, it is preferable to start from doping layerB and end at doping layer B. For example, a constitution of BAB, BABAB,BABABAB, or BABABABAB is preferable.

In particular, when the transparent electrode and the p-type layerand/or the n-type layer having a lamination structure are in contactwith each other, contact between doping layer B and the transparentelectrode is preferable because the diffusion of a Group III and/orGroup V element into indium oxide or tin oxide constituting thetransparent electrode can be prevented, so that the decrease inphotoelectric conversion efficiency of the photovoltaic element overtime can be suppressed.

The constitution of a photovoltaic element according to the presentinvention will be now described in detail.

Conductive Substrate

The conductive substrate may be directly a conductive member itself, ormade by forming a support of an insulating material or conductivematerial and having its surface subjected to conductive treatment.Examples of the conductive support include, for example, metals such asNiCr, stainless steel, Al, Cr, Mo, Au, Nb, Ta, V, Ti, Pt, Pb, Sn, andalloys thereof.

Examples of electrically insulating supports include synthetic resinfilms or sheets such as polyester, polyethylene, polycarbonate,cellulose acetate, polypropylene, polyvinylchloride, polyvinylidenechloride, polystyrene, and polyamide, glass, ceramics, and paper. Suchelectrical insulating supports preferably have at least one surfacethereof subjected to conductive treatment.

For example, if glass is used, a thin film of NiCr, Al, Cr, Mo, Ir, Nb,Ta, V, Ti, Pt, Pb, In₂ O₃, or ITO (In₂ O₃ +SnO₂) is formed on thesurface to provide conductivity. If a synthetic resin film such as apolyester film is used, a metallic thin film of NiCr, Al, Ag, Pb, Zn,Ni, Au, Cr, Mo, Ir, Nb, Ta, V, Ti or Pt is formed on the surface byvacuum vapor deposition, electron beam vapor deposition or sputtering,or a laminate is made on the surface with any of the above metals toprovide conductivity on the surface. The shape of the support may be asheet having a smooth or irregular surface. Its thickness can beappropriately determined to form a photovoltaic element as desired, butif the photovoltaic element is required to be flexible, the supportshould be formed as thin as possible as long as it can sufficientlyexhibit its necessary function. However, for the convenience offabricating or processing the support, the thickness is usually 10 μm orgreater from the point of mechanical strength.

Light Reflecting Layer

The light reflecting layer is suitably made of a metal having highreflectance in the visible to near infrared region, such as Ag, Al, Cu,or AlSi. It is preferable to form these metals by resistance heatingvacuum vapor deposition, co-vapor deposition, or sputtering. The layerthickness of these metals as the light reflecting layer suitably is from10 to 5000 nm. To texturize these metals (concave and convex), it isnecessary that the substrate temperature of these metals duringdeposition be above 200° C.

Light Reflection Multiplying Layer

The light reflection multiplying layer is optimally made of ZnO, SnO₂,In₂ O₃, ITO, TiO₂, CdO, Cd₂ Sn₄, Bi₂ O₃, MoO₃, or NaxWO₃.

The deposition method of the reflection multiplying layer preferably isa vacuum vapor deposition method, a sputtering method, a CVD method, aspray method, a spin-on method, or a dip method.

The layer thickness of the reflection multiplying layer may bedifferent, depending on the refractive index of the material for thereflection multiplying layer, and preferably is in a range from 50 nm to10 μm.

Further, to texturize the reflection multiplying layer, the substratetemperature during depositing the layer is preferably set above 300° C.

p-type Layer or n-type Layer

The p-type layer and the n-type layer are important layers governing thecharacteristics of the photovoltaic element.

The amorphous materials (denoted as "a-" but including crystallinematerials, denoted as "μc-", in the category of amorphous materials) mayinclude a-Si:H, a-Si:HX, a-SiC:H, a-SiC:HX, a-SiGe:H, a-SiGeC:H,a-SiO:H, a-SiN:H, a-SiON:HX, a-SiOCN:HX, μc-Si:H, μc-SiC:H, μc-Si:HX,μc-SiC:HX, μc-SiGe:H, μc-SiO:H, μc-SiGeC:H, μc-SiN:H, μc-SiON:HX, andμc-SiOCN:HX with the addition of a p-type valence control agent (e.g.,Group III atoms such as B, Al, Ga, In, Tl) or an n-type valence controlagent (e.g., Group V atoms such as P, As, Sb, Bi) at high concentration;and the polycrystalline materials (denoted as "poly-") may includepoly-Si:H, poly-Si:HX, poly-SiC:H, poly-SiC:HX, poly-SiGe:H, poly-Si,poly-SiC, and poly-SiGe with the addition of a p-type valence controlagent (e.g., Group III atoms such as B, Al, Ga, In, Tl) or an n-typevalence control agent (e.g., Group V atoms such as P, As, Sb, Bi) athigh concentration.

In particular, for the p-type layer or n-type layer on the lightincident side, a crystalline semiconductor layer with reduced lightabsorption or an amorphous semiconductor layer having a wider bandgap issuitable.

The amount of Group III atoms added to the p-type layer or the amount ofGroup V atoms added to the n-type layer is optimally in a range from 0.1to 50 at %.

Hydrogen atoms (H, D) or halogen atoms (X) contained in the p-type orn-type layer act to compensate dangling bonds in the p-type or n-typelayer and to improve the doping efficiency of the p-type or n-typelayer. The amount of hydrogen or halogen atoms added to the p-type orn-type layer is optimally in a range from 0.01 to 40 at %. Inparticular, when the p-type or n-type layer is crystalline, the contentof hydrogen or halogen atoms is optimally from 0.1 to 8 at %. Further, apreferable distribution of hydrogen and/or halogen atoms is such that agreater concentration is present at each interface of p-typelayer/i-type layer and n-type layer/i-type layer, the concentration ofhydrogen and/or halogen atoms near the interface being preferably 1.1 to2 times that within the bulk. In this way, by providing the greaterconcentration of hydrogen or halogen atoms near each interface of p-typelayer/i-type layer and n-type layer/i-type layer, the defect level ormechanical distortion near the interface can be decreased, resulting inincreased photovoltaic power or photocurrent of the photovoltaic elementof the present invention.

Of the electrical characteristics of the p-type or n-type layer in thephotovoltaic element, the activation energy is preferably 0.2 eV orless, and optimally 0.1 eV or less. The specific resistance ispreferably 100 Ωcm or less, and optimally 1 Ωcm or less. The layerthickness of the p-type or n-type layer is preferably from 10 to 500 Å,and optimally from 30 to 100 Å.

The source gases suitable for the deposition of the type or n-type layerfor the photovoltaic element include, for example, gasifiable compoundscontaining germanium atoms, gasifiable compounds containing nitrogenatoms and mixtures thereof.

Specifically, the gasifiable compounds containing silicon atoms includeSiH₄, Si₂ H₆, SiF₄, SiFH₃, SiF₂ H₂, SiF₃ H, Si₃ H₈, SiD₄, SiHD₃, SiH₂D₂, SiH₃ D, SiFD₃, SiF₂ D₂, SiD₃ H, and Si₂ D₃ H₃.

Also, specifically, the gasifiable compounds containing germanium atomsinclude GeH₄, GeD₄, GeF₄, GeFH₃, GeF₂ H₂, GeF₃ H, GeHD₃, GeH₂ D₂, GeH₃D, Ge₂ H₆, and Ge₂ D₆.

Further, specifically, the gasifiable compounds containing carbon atomsinclude CH₄, CD₄, C_(n) H_(2n+2) (n is an integer), C_(n) H_(2n) (n isan integer), C₂ H₂, C₆ H₆, CO₂, and CO.

The nitrogen-containing gases include N₂, NH₃, ND₃, NO, NO₂, and N₂ O.

Also, the oxygen-containing gases include O₂, CO, CO₂, NO, NO₃, N₃ O,CH₃ CH₂, OH, and CH₃ OH.

The substances introduced into the p-type or n-type layer for thevalence electron control include Group III and Group V atoms.

The starting materials effectively used for the introduction of GroupIII atoms include boron hydrides such as B₂ H₆, B₄ H₁₀, B₅ H₉, B₆ H₁₁,B₆ H₁₀, B₆ H₁₂, and B₆ H₁₄, and boron halides such as BF₃ and BCl₃, forthe introduction of boron atoms. Also, AlCl₃, GaCl₃, InCl₃, and TlCl₃may be included. B₂ H₆ and BF₃ are particularly suitable.

The starting materials effectively used for the introduction of Group Vatoms include phosphorus hydrides such as PH₃ and P₃ H₄, and phosphorushalides such as PH₄ I, PF₃, PF₅, PCl₃, PCl₅, PBr₃, PBr₅, and PI₃, forthe introduction of phosphorus atoms. Besides these, AsH₃, AsF₃, AsCl₃,AsBr₃, AsF₅, SbH₃, SbF₃, SbF₅, SbCl₃, SbCl₅, BiH₃, BiCl₃, and BiBr₃ mayalso be included. PH₃ and PF₅ are particularly suitable.

The deposition method of the p-type or n-type layer suitable for thephotovoltaic element relies on RF plasma CVD or microwave plasma CVD. Ofthe RF plasma CVD methods for deposition, an RF plasma CVD method of thecapacitive coupling type is particularly suitable.

In depositing the p-type or n-type layer by the RF plasma CVD, theoptimal conditions are such that the substrate temperature within thedeposition chamber is from 100° to 350° C., the internal pressure isfrom 0.1 to 10 Torr, the RF power is from 0.01 to 5.0 W/cm², and thedeposition rate is from 0.1 to 30 Å/sec.

Also, the gasifiable compound as previously noted may be introduced intothe deposition chamber by diluting it with a gas such as H₂, He, Ne, Ar,Xe, or Kr.

In particular, when depositing a layer having reduced light absorptionor a wide bandgap such as a crystalline semiconductor or a-SiC:H, it ispreferable to dilute the source gas to two to 100 times thereof withhydrogen gas and introduce a relatively high RF power. The RF frequencyis preferably in a range from 1 MHz to 100 MHz, and a frequency near13.56 MHz is particularly preferable.

When depositing the p-type or n-type layer by microwave plasma CVD, amicrowave plasma CVD apparatus, in which microwaves are introducedthrough a waveguide via a dielectric window (made of alumina ceramics)into the deposition chamber is suitable.

When depositing the p-type or n-type layer by microwave plasma CVD, amethod as previously described, of applying microwave power and RF powerto the source gas at the same time, is also suitable, but it is possibleto use wider deposition conditions for forming deposited filmsapplicable to the photovoltaic element. That is, when depositing thep-type layer or n-type layer by typical microwave plasma CVD methods, itis preferable that the substrate temperature within the deposition cheeris from 100° to 400° C., the internal pressure is from 0.5 to 30 mTorr,the microwave power is from 0.01 to 1 W/cm₃, and the microwave frequencyis from 0.5 to 10 GHz.

The gasifiable compound as previously cited may be introduced into thedeposition cheer by diluting it with a gas such as H₂, He, Ne, Ar, Xe,or Kr.

In particular, when depositing a layer having reduced light absorptionor a wide bandgap, such as a crystalline semiconductor or a-SiC:H, it ispreferable to dilute the source gas 2 to 100 times with hydrogen gas andintroduce a relatively high microwave power.

i-type Layer Formed by Microwave Plasma CVD

The i-type layer found by microwave plasma CVD in the photovoltaicelement is an important layer for generating and transporting chargecarriers by illuminating light thereon. The i-type may be slightlyp-type or slightly n-type.

The i-type layer of the photovoltaic element of the present invention isa layer containing silicon and geranium atoms and having its bandgapsmoothly changing in the direction of layer thickness thereof, theminimum value of bandgap being displaced in the direction of theinterface between the p-type layer and the n-type layer, away from thecentral position of the i-type layer. Also, it is preferred that avalence electron control agent as a donor and a valence electron controlagent an acceptor be doped in the i-type layer at the same time.

Hydrogen atoms (H, D) or halogen atoms (X) contained in the i-type layeract to compensate dangling bonds of the i-type layer and to enhance theproduct of the mobility and the lifetime charge of carriers in thei-type layer. Also, these atoms compensate the interfacial levels ateach n-type layer/i-type layer interface, with the effect of enhancingthe photovoltaic power, photocurrent, and light response of thephotovoltaic element. The content of hydrogen and/or halogen atoms inthe i-type layer is optimally in a range from 1 to 40 at %. Inparticular, a preferable distribution is such that a greaterconcentration of hydrogen and/or halogen atoms is present at each n-typelayer/i-type layer interface, the concentration of hydrogen and/orhalogen atoms changing corresponding to the content of silicon atoms.The content of hydrogen and/or halogen atoms is preferably from 1 to 10at %, when the content of silicon atoms is at a minimum, and preferably0.3 to 0.8 times the maximum content of hydrogen and/or halogen atoms.

The concentration of hydrogen and/or halogen atoms is changedcorresponding to the content of silicon atoms. that is, corresponding tothe bandgap, such that the content of hydrogen and/or halogen atoms issmaller in the narrower bandgap region. The detailed mechanism is notknown, but in accordance with the deposited film forming method of thepresent invention, in depositing an alloy-type semiconductor containingsilicon and germanium atoms, different RF energies are absorbed byrespective atoms due to the difference in ionization rate betweensilicon and germanium atoms, causing sufficient relaxation even with asmaller content of hydrogen and/or halogen in the alloy-typesemiconductor, so that an alloy-type semiconductor of high quality canbe deposited.

In addition, by adding a slight amount of oxygen and/or nitrogen, i.e.100 ppm or less, to the i-type layer containing silicon and germaniumatoms, the photovoltaic element has greater durability against annealingover the long term. The detailed reason is not known, but may beconsidered to be as described below. That is, since the compositionration of silicon and germanium atoms continuously changes in thedirection of layer thickness, there is a tendency of having moreresidual distortion than when the silicon and germanium atoms are mixedat a fixed ratio. It is believed that by adding oxygen and/or nitrogenatoms at such a layer, structural distortion can be reduced, so that thephotovoltaic element has greater durability against annealing over thelong term. A preferable distribution is such that the concentration ofoxygen and/or nitrogen atoms in the direction of layer thicknessincreases or decreases corresponding to the concentration of germaniumatoms. This distribution is inverse to the distribution of hydrogenand/or halogen atoms, but is believed preferable for both removingstructural distortion and reducing dangling bonds.

Further, with such a distribution of hydrogen (and/or halogen) atoms andoxygen (and/or nitrogen) atoms, the tail states of the valence band andthe conduction band can be connected smoothly and continuously.

The layer thickness of the i-type layer is optimally from 0.05 to 1.0μm, although it may depend on the structure of the photovoltaic element(e.g., single cell, tandem cell, triple cell) and the bandgap of thei-type layer.

The i-type layer containing silicon and germanium atoms formed by thedeposited film forming method of the present invention has few tailstates on the valence band side even if the deposition rate is increasedto 5 nm/sec or greater. The inclination of the tail states is 60 meV orless, and the density of dangling bonds due to electron spin resonance(esr) is 10¹⁷ /cm³ or less.

Also, it is preferable that the bandgap of the i-type layer be wider ateach interface of p-type layer/i-type layer and n-type layer/i-typelayer. Such a design increases the photovoltaic power and photocurrentof the photovoltaic element and prevents optical deterioration due touse over a long time.

For forming the i-type layer of the photovoltaic element, the depositedfilm forming method as previously described of applying microwave andhigh frequency (RF) simultaneously is an optimal method.

i-type Layer Formed by RF Plasma CVD

The i-type layer formed by RF plasma CVD is deposited at a rate of 1nm/sec or less, the content of hydrogen and/or halogen atoms in thedeposition film being preferably from 1 to 40 at %. The bonding state ofhydrogen or halogen atoms is preferably one wherein a single hydrogen orhalogen atom is bonded with a silicon atom. It is preferable that thehalf-width value of a peak of 2000 cm⁻¹, divided by the height of thepeak, in the infrared absorption spectrum representing the state whereone hydrogen atom is bonded with a silicon atom is greater than thevalue of half-width at the peak of 2000 cm⁻¹, divided by the height ofpeak, for the i-type layer by microwave plasma CVD.

Transparent Electrode

The transparent electrode is suitable made of indium oxide or indium-tinoxide. The optimal deposition methods for the transparent electrode area sputtering method and a vacuum vapor deposition method.

The transparent electrode is deposited in a manner as described below.

When the transparent electrode composed of indium oxide is deposited onthe substrate with a DC magnetron sputtering apparatus, the target maybe made of metallic indium (In) or indium oxide (In₂ O₃).

Further, when the transparent electrode composed of indium-tin oxide isdeposited on the substrate, the target may be an appropriate combinationof targets of metallic tin, metallic indium, an alloy of metallic tinand metallic indium, tin oxide, indium oxide, or indium-tin oxide.

When deposition is made by sputtering, the substrate temperature is animportant factor, the preferable range being from 25° to 600° C. Whendepositing the transparent electrode by sputtering, the sputtering gasesmay include inert gases such as argon gas (Ar), neon gas (Ne), xenon gas(Xe), and helium gas (He), among which Ar gas is particularlypreferable. Also, it is preferable to add oxygen gas (O₂) to the inertgas as necessary, and particularly when metal is used as the target,oxygen gas (O₂) is requisite.

Further, when the target is sputtered with an inert gas, the pressure inthe discharge space is preferably from 0.1 to 50 mTorr for effectivesputtering.

In addition, the electric power source for the sputtering may be a DCpower source or an RF power source. The applied power during thesputtering is preferably in a range from 10 to 1000 W.

The deposition rate for the transparent electrode depends on thepressure within the discharge space or the discharge power, andoptimally is in a range from 0.01 to 10 nm/sec.

In the vacuum vapor deposition, the vapor deposition source suitable forthe deposition of transparent electrode may be metallic tin, metallicindium, or indium-tin alloy.

Also, the substrate temperature in depositing the transparent electrodeis in a range from 25° to 600° C.

Further, when depositing the transparent electrode, it is necessary thatafter the pressure reduction of the deposition chamber to 10⁻⁵ Torr orless, oxygen gas (O₂) is introduced into the deposition chamber in arange from 5×10⁻⁵ to 9×10⁻⁴ Torr. By introducing oxygen in this range,the metal gasified from the vapor deposition source will react withoxygen in the gas phase to deposit an excellent transparent electrode.

In addition, it is possible to introduce RF power with a degree ofvacuum as above noted to produce a plasma, with which the vapordeposition is made.

The preferable deposition rate of the transparent electrode under theabove conditions is from 0.01 to 10 m/sec. If the deposition rate isbelow 0.01 nm/sec, the productivity is lowered, while if it is greaterthan 10 nm/sec, a rough film may be produced, resulting in lowertransmittance, conductivity, or adherence.

It is preferred that the layer thickness of the transparent electrodemeets the conditions of an antireflection film. Specifically, the layerthickness of the transparent electrode preferably ranges from 50 to 300nm.

A power generation system of the present invention is comprised of aphotovoltaic element of the present invention, a control system forcontrolling the supply of electric power from the photovoltaic elementto an accumulator and/or an external load by monitoring the voltageand/or current of the photovoltaic element, and the accumulator foraccumulating the electric power from the photovoltaic element and/orsupplying the electric power to the external load.

FIG. 27 is an example of a power supply system of the present invention,which is a basic circuit having only the photovoltaic element as thepower source, wherein the power supply system is comprised of aphotovoltaic element 9001 of the present invention as a solar cell, adiode 9002 for the voltage control of the photovoltaic element, acondenser 9003 for the voltage stabilization and acting as theaccumulator, a load 9004, and a reverse current preventing diode 9005.

FIG. 28 is an example of a power supply system of the present invention,which is a basic charging circuit using a photovoltaic element. Thecircuit is comprised of solar cell 9101 which is a photovoltaic elementof the present invention, reverse current preventing diode 9102, voltagecontrol circuit 9103 for controlling the voltage by monitoring it,secondary cell 9104, and load 9105. The reverse current preventing diodesuitably may be a silicon diode or Schottky diode. The secondary cellmay be a nickel cadmium cell, rechargeable silver oxide cell, leadaccumulator, and flywheel energy accumulating unit. FIG. 29 is anexample of voltage control circuit 9103. The voltage control circuitoutputs a voltage approximately equal to the output from the solar cellunit the cell is fully charged, but stops the charging current by acharging control IC if the cell is fully charged.

The solar cell system utilizing such photovoltaic power can be used asthe battery for an automobile battery charging system, a marine batterycharging system, a street lamp lighting system, and an exhaust system.

FIG. 30 is a block diagram of a solar cell, a diesel dynamo, and a powersupply system of the hybrid type. The power generation system iscomprised of diesel dynamo 9401, solar cell 9402 having a group ofphotoelectric conversion elements, rectifier 9403, charge/dischargecontrol unit 9404, accumulator 9405, DC/AC conversion unit 9406 as apower conversion means, switch 9407, and AC load 9408.

Further, FIG. 31 is a block diagram of a solar cell power supply systemof commercially available backup type. The power supply system iscomprised of a solar cell 9501 which is a photoelectric conversionelement, a charge/discharge control unit 9502, an accumulator 9503, aDC/AC conversion unit 9504 as a power conversion means, a commerciallyavailable power source 9505, a non-instantaneous switch 9506, and a load9507.

In addition, FIG. 32 is a block diagram of a commercially availablesolar cell power supply system of complete link type. The power supplysystem is comprised of a solar cell 9601 which is a photoelectricconversion element, a DC/AC converter 9602 as power conversion means, acommercially available power source 9603, a load 9604, and a reversecurrent 9605.

As described above, a power supply system, utilizing a photovoltaicelement of the present invention as the solar cell, can be stably usedfor a long period, and sufficiently function as a photovoltaic elementeven when the illuminating light directed to the solar cell varies, withexcellent stability.

EXAMPLES

The present invention will now be described in more detail by way ofexample, but the invention is not limited to such samples.

Example 1

Using a microwave plasma CVD apparatus comprising source gas supply unit1020 and deposition unit 1000 as shown in FIG. 18 and an RF plasma CVDapparatus comprising source gas supply unit 1020 and deposition unit1100 as shown in FIG. 19, a photovoltaic element of the presentinvention was fabricated.

Gas cylinders 1071 to 1079 in the figure contain source gases for thefabrication of a p-type layer, an i-type layer, and an n-type layercomposed of silicon non-single crystalline semiconductor material of thepresent invention, wherein 1071 is an SiH₄ gas cylinder, 1072 is acylinder of H₂ gas, 1073 is a cylinder of BF₃ gas diluted to 1% with H₂gas (hereinafter abbreviated as "BF₃ 3(1%)/H₂ "), 1074 is a cylinder ofPH₃ gas diluted to 1% with H₂ gas (hereinafter abbreviated as "PH₃(1%)/H₂ "), 1075 is a cylinder of Si₂ H₆ gas, 1076 is a cylinder of GeH₄gas, 1077 is a cylinder of BF₃ gas diluted to 2000 ppm with H₂ gas(hereinafter abbreviated as "BF₃ (2000 ppm)/H₂ "), 1078 is a cylinder ofPH₃ gas diluted to 2000 ppm with H₂ gas (hereinafter abbreviated as "PH₃(2000 ppm)/H₂ "), and 1979 is a cylinder of NO gas diluted to 1% with Hegas (hereinafter abbreviated as "NO/He"). Also, the gases are eachpreintroduced through the valves 1051 to 1059 via inlet valves 1031 to1039 into the gas pipes when mounting the gas cylinders 1071 to 1079.

In the FIGS. 1004 and 1104 are substrates, made of stainless (SUS430BA),50 mm square and 1 mm thick, each with its surface polished specularly,having a 100 nm-thick silver (Ag) thin film, made irregular, as thereflecting layer and a 1 μm-thick zinc oxide (ZnO) layer there as thereflection multiplying layer, which layers are deposited by sputtering.

First, SiH₄ gas from the gas cylinder 1071, H₂ gas from the gas cylinder1072, BF₃ (1%)/H₂ gas from the gas cylinder 1073, PH₃ (1%)/H₂ gas fromthe gas cylinder 1074, Si₂ H₆ gas from the gas cylinder 1075, GeH₄ gasfrom the gas cylinder 1076, BF₃ (2000 ppm)/H₂ gas from the gas cylinder1077, PH₃ (2000 ppm)/H₂ gas from the gas cylinder 1078, and NO/He gasfrom the gas cylinder 1079 were introduced by opening the valves 1051 to1059, whereby each gas pressure was regulated by each pressure regulator1061 to 1069 to about 2 Kg/cm².

Next, confirming that the inflow valves 1031 to 1039 and leak valves1009, 1109 within the deposition chambers 1001, 1101 were closed, andthat the outflow valves 1041 to 1049 and auxiliary valves 1008, 1108were open, conductance (butterfly type) valves 1007, 1107 were fullyopened to evacuate the deposition cheers 1001, 1101 and the gas pipe byusing a vacuum pump (not shown) and the auxiliary valves 1008, 1108 andthe outflow valves 1041 to 1049 were closed at the time when the readingof vacuum gauges 1006, 1106 reached about 1×10⁻⁴ Torr.

Next, the inflow valves 1031 to 1039 were gradually opened to introducerespective gases into the mass flow controllers 1021 to 1029.

After the preparation for the film formation has been completed in theabove way, an n-type layer, an i-type layer formed by microwave plasmaCVD, an i-type layer formed by RF plasma CVD, and a p-type layer wereformed on the substrates 1004, 1104.

To make the n-type layer, the substrate 1004 was heated to 350° C. bythe heater 1005, the outflow valves 1041 to 1044 and the auxiliary valve1008 were gradually opened to flow SiH₄ gas and PH₃ (1%)/H₂ gas throughthe gas introducing pipe 1003 into the deposition chamber 1001. Then,they were regulated by mass flow controllers 1021, 1024 so that the SiH₄gas flow and the PH₃ (1%)/H₂ gas flow were 50 sccm and 200 sccm. Theopening of conductance valve 1007 was adjusted by referring to thevacuum gauge 1006 so that the pressure within the deposition chamber1001 was 10 mTorr.

Thereafter, shutter 1013 was closed, and the direct current (hereinafterabbreviated as "DC") bias of bias power source 1011 was set at 50 V andapplied to bias rod 1012. Subsequently, the output power of themicrowave power source (not shown), was set at 130 mW/cm³, and microwaveelectric power was introduced through the wavequide (not shown),waveguide portion 1010, and dielectric window 1002 into depositionchamber 1001 to excite a microwave glow discharge. Then, shutter 1013was opened to start formation of the n-type layer on substrate 1004.Upon depositing the n-type layer 10 nm thick, shutter 1013 was closed tostop microwave glow discharge, and outflow valves 1041, 1044 andauxiliary valve 1008 were closed to stop the gas inflow into depositionchamber 1001, whereby the fabrication of the n-type layer was completed.

Next, to make the i-type layer by microwave plasma CVD, the substrate1004 was heated to 350° C. by the heater 1005, and the outflow valves1041, 1042, 1046, and the auxiliary valve 1008 were gradually opened toflow SiH₄ gas, H₂ gas, and GeH₄ gas, respectively, through the gasintroducing tube 1003 into the deposition chamber 1001. Then, they wereregulated by mass flow controllers 1021, 1022, 1026 so that SiH₄ gasflow, H₂ gas flow, and GeH₄ gas flow were 200 sccm, 500 sccm, and 1sccm. The opening of conductance valve 1007 was adjusted by referring tothe vacuum gauge 1006 so that the pressure within the deposition chamber1001 reached a value as indicated in Table 2.

Next, the shutter 1013 was closed, the output power of the microwavepower source (not shown) was set at 170 mW/cm³, and microwave electricpower was introduced through the waveguide, the waveguide portion 1010,and the dielectric window 1002 into the deposition chamber 1001 toexcite a microwave glow discharge. The radio frequency (abbreviated as"RF") bias of bias power source 1011 was set at 350 mW/cm³, and the DCbias was set at 0 V via a coil, which was then applied to the bias rod1012. Thereafter, the shutter 1013 was opened to start formation of thei-type layer by microwave plasma CVD on the n-type layer, and at thesame time, SiH₄ gas flow and GeH₄ gas flow were adjusted in accordancewith a flow pattern as shown in FIG. 16A by the mass flow controllers1021, 1026. Upon depositing the i-type layer having a layer thickness of300 nm, the shutter 1013 was closed, the output of bias power source1011 was turned off, the microwave glow discharge was stopped, and theoutflow valves 1041, 1042, 1046, and the auxiliary valve 1008 wereclosed stop the gas inflow into the deposition chamber 1001.

Then, the substrate 1004 was taken out from the deposition chamber 1001,and installed in the deposition chamber 1101 of the RF plasma CVDdeposition apparatus 1100 where the i-type layer formed by RF plasma CVDwas fabricated.

Next, to deposit the i-type layer formed by RF plasma CVD, the substrate1104 was heated to 350° C. by the heater 1105, and the outflow valves1041, 1042, and the auxiliary valve 1008 were gradually opened to flowSiH₄ gas and H₂ gas through the gas introducing tube 1103 into thedeposition chamber 1101. Then, they were regulated by mass flowcontrollers 1021, 1022 so that SiH₄ gas flow and H₂ gas flow were 8 sccmand 100 sccm. The opening of conductance valve 1107 was adjusted byreferring to the vacuum gauge 1106 so that the pressure within thedeposition chamber 1101 became 0.5 Torr.

Thereafter, the output power of RF power source 1111 was set at 120mW/cm³, and RF electric power was introduced through the RF matching box1112 into the cathode 1102 to excite an RF glow discharge. Thedeposition of the i-type layer found by RF plasma CVD was started on thei-type layer made by microwave plasma CVD. Upon depositing an i-typelayer having a layer thickness of 10 nm, the RF glow discharge wasstopped, and the outflow valves 1041, 1042 and the auxiliary valve 1108were closed to stop the gas inflow into the deposition chamber 1101,whereby the fabrication of the i-type layer was completed.

Then, the substrate 1104 was taken out from the deposition chamber 1101,and installed in the deposition chamber 1001 of the microwave plasma CVDdeposition apparatus 1000 as shown in FIG. 18, where the p-type layerwas fabricated.

To make the p-type layer, the substrate 1004 was heated to 300° C. bythe heater 1005, the outflow valves 1041 to 1043 and the auxiliary valve1008 were gradually opened to flow SiH₄ gas, H₂ gas, and BF₃ (1%)/H₂gas, respectively, through the gas introducing tube 1003 into thedeposition chamber 1001. Then, they were regulated by mass flowcontrollers 1021 to 1023 so that the SiH₄ gas flow, H₂ gas flow, and BF₃(1%)/H₂ gas flow were sccm, 700 sccm, and 30 sccm. The opening ofconductance valve 1007 was adjusted by referring to the vacuum gauge1006 so that the pressure within the deposition chamber 1001 was 25mTorr.

Thereafter, the output power of the microwave power source (not shown)was set at 250 mW/cM³, and microwave electric power was introducedthrough the waveguides (not shown), the waveguide portion 1010, and thedielectric window 1002 into the deposition chamber 1001 to excite amicrowave glow discharge. And the shutter 1011 was opened to startfabrication of the p-type layer on the i-type layer by RF plasma CVD.Upon making the p-type layer 10 nm thick, the shutter 1013 was closed,the microwave glow discharge was stopped, and the outflow valves 1041 to1043 and the auxiliary valve 1008 were closed to stop the gas inflowinto the deposition cheer 1001, whereby the fabrication of the p-typelayer was completed.

Outflow valves 1041 to 1049 other than those of the necessary gases arefully closed during deposition of the respective layers. In order toprevent each of the gases from remaining within the deposition chambers1001, 1101 and the pipes leading from the outflow valves 1041 to 1049 tothe deposition chambers 1001, 1101, the operation of closing the outflowvalves 1041 to 1049, opening the auxiliary valves 1008, 1108, andfurther fully opening the conductance valves 1007, 1107 to evacuate thesystem into high vacuum may be conducted, as required.

Next, on the p-type layer, a 70 μm-thick ITO (In₂ O₃ +SnO₂) thin film asthe transparent electrode and a 2 μm-thick aluminum (Al) thin film asthe collector electrode were vapor deposited in vacuum to fabricatephotovoltaic elements (Element No. Examples 1-1 to 1-7 and ComparativeExample 1-1). The fabrication conditions for the photovoltaic element asdescribed above are listed in Table 1.

The initial characteristics, low illuminance characteristic, anddurability characteristic were measured for the fabricated photovoltaicelement.

The measurement of the initial characteristics was performed in terms ofthe open-circuit voltage and fill vector obtained by placing thefabricated photovoltaic elements under illumination of light with AM-1.5(100 mW/cm²) and measuring the V-I characteristic. The results arelisted in Table 2.

The measurement of the low illuminance characteristic was performed interms of the photovoltaic conversion efficiency obtained by placing thefabricated photovoltaic elements under illumination of light with AM-1.5(10 mW/cm²) and measuring the V-I characteristic. The results are listedin Table 2.

The measurement of the durability characteristic was performed in termsof the change in the photoelectric conversion efficiency obtained byplacing the fabricated photovoltaic elements in the dark at a humidityof 70% and a temperature of 60° C. and then applying vibrations of 1 mmat 3600 rpm 48 hours. The results are listed in Table 2.

As seen in Table 2, a photovoltaic element having excellentcharacteristics is fabricated by making the i-type layer by microwaveplasma CVD under a pressure of the deposition chamber 1001 of 50 mTorror less.

Next, using a substrate of barium borosilicate glass (7059 manufacturedby Corning), an i-type layer formed by microwave plasma CVD wasdeposited on the substrate by opening the shutter 1013 for two minutesunder the same conditions as the i-type layer formed by microwave plasmaCVD in Element No. Example 1-5, except that the SiH₂ gas flow and GeH₄gas flow and the microwave electric power were as indicated in Table 3,whereby samples for the measurement of source gas decompositionefficiency were fabricated (Sample Nos. 1-1 to 1-5).

The film thickness of the fabricated sample for the measurement ofsource gas decomposition efficiency was measured by a layer thicknessmeasuring instrument (Alpha Step 100 manufactured by TENCOR INSTRUMENTS)obtain the decomposition efficiency of source gas. The results arelisted in Table 3.

Then, photovoltaic elements were fabricated (Element No. Examples 1-8 to1-10 and Comparative Examples 1-2 to 1-3) by forming a reflecting layer,a reflection multiplying layer, an n-type layer, an i-type layer, ap-type layer, a transparent electrode, and a collector electrode on thesubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 1-5, except that the microwave electric power wasas indicated in Table 4 for depositing the i-type layer formed bymicrowave plasma CVD.

For the fabricated photovoltaic, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Element No. Example 1-5. The resultsare listed in Table 4.

As will be seen from Tables 3 and 4, a photovoltaic element havingexcellent characteristics can be obtained by decomposing the source gaswith a lower microwave energy than the microwave energy necessary todecompose 100% of the source gas.

Then, photovoltaic elements were fabricated (Element No. Examples 1-11to 1-14 and Comparative Example 1-4) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on thesubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 1-5, except that the RF bias was as indicated inTable 5 during deposition of the i-type layer formed by microwave plasmaCVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 1-5. Theresults are listed in Table 5. As will be seen from Table 5, aphotovoltaic element having excellent characteristics can be obtained byapplying a higher RF energy to the source gas than the microwave energy.

Next, using a stainless steel substrate and a barium borosilicate glass(7059 manufactured by Corning) substrate, an i-type layer 1 μm thick wasformed on the substrate under the same conditions as the substrate underthe same conditions as the i-type layer formed by microwave plasma CVDin Element No. Example 1-5, except that SiH₄ gas flow and GeH₄ gas flowwere as indicated in Table 6, whereby samples for the measurement of thematerial were fabricated (Sample Nos. 1-6 to 1-10).

Further, using a barium borosilicate glass (7059 manufactured byCorning) substrate, an i-type layer 1 μm thick was formed on thesubstrate under the same fabrication conditions as the i-type layerformed by RF plasma CVD in Element No. Example 1-5, whereby a sample forthe measurement of the material was fabricated (Sample No. 1-11).

The bandgap and the composition of the fabricated samples for themeasurement of the materials were determined to obtain the relationbetween the composition ratio of Si to Ge atoms and the bandgap.

The measurement of the bandgap was performed by installing the glasssubstrate having the i-type layer fabricated thereon in aspectrophotometer (330 type manufactured by Hitachi, Ltd.) to measurethe wavelength dependency of absorption coefficient for the i-type layerand obtain the bandgap of the i-type layer in accordance with a methodas described in "Amorphous solar cells" (written by Kiyoshi Takahashiand Makato Konagai, published by Shokodo, p. 109).

The analysis of composition was performed by installing the stainlesssubstrate having the i-type layer fabricated thereon in an Augerelectron spectral analysis instrument (JAMP-3 manufactured by JEOL,Ltd.), and measuring the composition ratio of Si atoms to Ge atoms. Theresults of bandgap and composition are shown in Table 6.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 1-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of the photovoltaic element in Element No. Example1-5, except that the SiH₄ gas flow and the GeH₄ gas flow were regulatedby the mass flow controllers 1021, 1026 in accordance with the flowpatterns as shown in FIG. 26B during deposition of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 1-5. Theresults indicated that the open-circuit voltage and the fill factor ofthe initial characteristics, the low illuminance characteristic, and thedurability characteristic of Element No. Example 1-5 were 1.02 times,1.03 times, 1.08 times and 1.07 times better than those in ComparativeExample 1-5, respectively.

Next, the composition analysis in the layer thickness direction of theSi atoms and the Ge atoms in the i-type layer formed by microwave plasmaCVD in Element No. Example 1-5 and Element No. Comparative Example 1-5was performed in the same manner as the previous composition analysis.From the relation between the composition ratio and the bandgap of Siatoms to Ge atoms obtained by Sample Nos. 1-6 to 1-10 as previouslydescribed, the variation of the bandgap in the layer thickness directionof the i-type layer was obtained. The results are shown in FIG. 24. Aswill be seen from FIG. 24, the photovoltaic element of Element No.Example 1-5 has the minimum value of bandgap at position shifted towardthe interface between the p-type and the i-type layer, away from centralposition of the i-type layer, while the photovoltaic element of ElementNo. Comparative Example 1-5 has the minimum value of bandgap at aposition shifted toward the interface between the n-type layer and thei-type layer away from the central position of the i-type layer.

Then, photovoltaic elements were fabricated (Element No. Examples 1-15to 1-19 and Comparative Example 1-6) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on thesubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 1-5, except that the SiH₄ gas flow and RFdischarge power were as indicated in Table 7 during deposition of thei-type layer formed by RF plasma CVD.

For fabricated photovoltaic elements, the initial characteristics, thelow illuminance characteristic, and the durability characteristic weremeasured in the same manner as in Element No. Example 1-5.

Next, using a barium borosilicate glass (7059 manufactured by Corning)substrate, an i-type layer 1 μm thick was formed on the substrate underthe same conditions as the i-type layer formed on the substrate underthe same conditions as the i-type layer formed by RF plasma CVD inElement No. Example 1-5, except that the SiH₄ gas flow and RF dischargepower were as shown in Table 7, whereby a sample for the measurement ofdeposition rate was fabricated (Sample Nos. 1-12 to 1-17). Thedeposition rate of the fabricated sample was obtained in the same manneras in Sample Nos. 1-1 to 1-5. The results are listed in Table 7.

As will be seen from Table 7, it has been found that a photovoltaicelement having excellent characteristics can be obtained by making thei-type layer by RF plasma CVD at a deposition rate of 2 nm/sec or less.

Then, photovoltaic elements were fabricated (Element No. Examples 1-20to 1-22 and Comparative Examples 1-7 to 1-8) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode and a collector electrode on thesubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 1-5, except that the layer thickness of thei-type layer was as indicated in Table 8 during formation of the i-typelayer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 1-5. Theresults are listed in Table 8. As will be seen from Table 8, thephotovoltaic elements provided with the i-type layer formed by RF plasmaCVD having a layer thickness of 30 nm or less (Element No. Examples 1-20to 1-22) have excellent characteristics.

Using a single crystal silicon substrate, a 1 μm thick layer formed byRF plasma CVD was deposited on the substrate under the same conditionsas the i-type layer formed by RF plasma CVD in Element No. Example 1-5,except that the RF discharge power was as shown in Table 9, whereby asample for the measurement of the infrared spectrum was fabricated(Sample Nos. 1-18 to 1-22).

Further, using a single crystal silicon substrate, a 1 μm thick i-typelayer formed by microwave plasma CVD was deposited on the substrateunder the same conditions as the i-type layer formed by microwave plasmaCVD in Element No. Example 1-5, whereby a sample for the measurement ofthe infrared spectrum was fabricated (Sample No. 1-23).

The fabricated sample for the measurement of the infrared spectrum(Sample Nos. 1-18 to 1-23) was installed in an infraredspectrophotometer (1720-X manufactured by PERKIN ELMER) to obtain avalue of the half-width of a peak at 2000 cm⁻¹ in the infraredabsorption spectrum divided by the height of the peak. The results arelisted in Table 9.

Then, photovoltaic elements were fabricated (Element No. Examples 1-23to 1-26) by forming a reflecting layer, a reflection multiplying layer,an n-type layer, an o-type layer, a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of the photovoltaic element in Element No. Example1-5, except that RF discharge power was indicated in Table 9 duringformation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the infrared characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 1-5. Theresults are listed in Table 9. As will be seen from Table 9, thephotovoltaic element having a greater value of half-width of a peak at2000 cm⁻¹ in the infrared absorption spectrum divided by the height ofthe peak in the i-type layer was formed by RF plasma CVD rather than bymicrowave plasma CVD and has excellent characteristics.

From the above results, it has been found that the photovoltaic elements(Element No. Examples 1-1 to 1-23) of the present invention have bettercharacteristics than the conventional photovoltaic elements (Element No.Comparative Examples 1-1 to 1-8). The photovoltaic elements of thepresent invention have an i-type layer formed by microwave plasma CVD atan internal pressure of 50 mTorr or less by applying a lower microwaveenergy and a higher RF energy then the microwave energy necessary todecompose 100% of the source gas. An i-type layer formed by RF plasmaCVD is deposited to a thickness of 30 nm or less at a deposition rate of2 nm/sec or less, in such a manner that the bandgap smoothly changes inthe direction of layer thickness. The minimum value of bandgap occurs ata position shifted toward the interface between the p-type layer and thei-type layer, away from the central position of the i-type layer. Thus,the effects of the present invention have been evidenced.

Example 2

Photovoltaic elements were fabricated (Element No. Examples 2-1 to 2-8)by forming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 1-5 in Example 1, except that the SiH₄ gas flowand the GeH₄ gas flow were regulated by the mass flow controllers 1021,1026 in accordance with the flow patterns as shown in FIG. 13A. As inExample 1, the SiH₄ gas flow was maintained at 200 sccm and the GeH₄ gasflow at 1 sccm, and the region of the maximum value of bandgap had alayer thickness as indicated in Table 10 for making the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. The results are listedin Table 10. As will be seen from Table 10, the photovoltaic elements(Element No. Examples 2-1 to 2-7) having a layer thickness of 1 to 30 nmin the region of the maximum value of bandgap have excellentcharacteristics, whereby the effects of the present invention areevidenced.

Example 3

A photovoltaic element was fabricated (Element No. Example 3) by forminga reflecting layer, a transparent conductive layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as those of ElementNo. Example 1-5 in Example 1, except that the BF₃ (2000 ppm)/H₂ gas flowand PH₃ (2000 ppm)/H₂ gas flow were 0.04 sccm and 0.02 sccm, usingcylinder 1077 and cylinder 1078, respectively, during formation of thei-type layer by RF plasma CVD.

For Element No. Example 3, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Also, the composition analysis for Element No. Example 3 was performedusing a secondary ion mass spectrometer (IMS-3F manufactured by CAMECA),and it was confirmed that B atoms and P atoms were contained in thei-type layer formed by RF plasma CVD.

Example 4

A photovoltaic element was fabricated (Element No. Example 4) by forminga reflecting layer, a transparent conductive layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as those of ElementNo. Example 1-5 in Example 1, except that AsH₃ gas diluted to 2000 ppmwith H₂ gas (hereinafter abbreviated as "AsH₃ /H₂ ") was used instead ofPH₃ (2000 ppm)H₂ gas at a flow rate 0.1 sccm during formation of thei-type layer by RF plasma CVD.

For Element No. Example 4, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Example 5

A photovoltaic element was fabricated (Element No. Example 5) by forminga reflecting layer, a transparent conductive layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as those of ElementNo. Example 1-5 in Example 1, except that a cylinder of NO/He gas 1079was used at a flow rate of 0.5 sccm for the i-type layer formed bymicrowave plasma CVD and at 0.05 sccm for the i-type layer formed by RFplasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Also, composition analysis of Element No. Example 5 was performed usinga secondary ion mass spectrometer, and it was confirmed that N atoms andO atoms were contained in the i-type layer.

Example 6

A photovoltaic element was fabricated (Element No. Example 6) by forminga reflecting layer, a transparent conductive layer, a n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as Element No.Example 1-5, except that a cylinder of Si₂ H₆ gas was used at a flowrate of 40 sccm, regulated by a mass flow controller 1021 in accordancewith the flow pattern as shown in FIG. 25A during a formation of thei-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Also, the distribution in the layer thickness direction of the Si atomsand hydrogen atoms in the i-type layer of the photovoltaic element wereanalyzed using a secondary ion mass spectrometer (IMS-3F manufactured byCAMECA). The results are shown in FIG. 25B.

From the above results, it has been found that the photovoltaic elementin which the content of hydrogen atoms changes corresponding to thecontent of Si atoms has excellent characteristics, whereby the effectsof the present invention have been evidenced.

Example 7

A photovoltaic element was fabricated (Element No. Example 7) by forminga reflecting layer, a transparent conductive layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as those of ElementNo. Example 1-5, except that the distance between the point of mixingSiH₄ gas and GeH₄ gas and the deposition cheer 1001 in the source gassupply unit 1020 was set as listed in Table 11.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 1. Theresults are listed in Table 11. As will be seen from Table 11, if thedistance between the point of mixing SiH₄ gas and GeH₄ gas and thedeposition chamber 1001 is 5 m or less, a photovoltaic element havingexcellent characteristics can be obtained.

Example 8

A photovoltaic element was fabricated under the same conditions as inElement No. Example 1-5, and using this photovoltaic element, a solarcell module was fabricated, whereby an analog clock with a circuitconfiguration as shown in FIG. 28 was made. In FIG. 28, the electricpower generated by a solar cell module 9101 is passed via a reversecurrent preventing diode 9102 to charge a secondary cell 9104. 9103 isan overcharge preventing diode.

The electric power from the solar cell module 9101 and the secondarycell 9104 is supplied to a drive circuit 9105 of the analog clock.

Comparative Example 2

As a comparative example, a photovoltaic element was fabricated as inElement No. Comparative Example 1-7, and using this photovoltaicelement, the same analog clock as in Example 8 was made.

The analog clocks as fabricated in Example 8 and the Comparative Example2 were installed on the wall of a room, and an indoor lamp was lit for8.5 hours a day. As a result, the analog clock of Example 8 worked theentire day, but the analog clock of the comparative example did not workthe entire day, whereby the effects of the power generation system ofthe present invention could be evidenced.

Example 9

A photovoltaic element was fabricated (Element No. Example 9) by forminga reflective layer, a transparent conductive layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on the substrate under the same conditions as those of ElementNo. Example 1-5 in Example 1, except that the flow rates of SiH₄ gas andGeH₄ gas were regulated by mass flow controllers 1021, 1026 inaccordance with the flow patterns as shown in FIG. 26 during formationof the i-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner in Example 1, and the results wereequivalent to those of Element No. Example 1-5, whereby the effects ofthe present invention were evidenced.

Example 10

A photovoltaic element was fabricated (Element No. Example 10) byforming a reflective layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 1-5 in Example 1, except B₂ H₆ gas diluted to 1%with H₂ gas (hereinafter abbreviated as "B₂ H₆ (1%)/H₂ ") was usedinstead of BF₃ (2000 ppm)/H₂ gas at a flow rate 0.05 sccm duringformation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5, whereby the effects ofthe present invention were evidenced.

Example 11

A photovoltaic element was fabricated (Element No. Example 11) byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 1-5 in Example 1, except that the flow of NO/Hegas was regulated by a mass flow controller 1029 in accordance with theflow pattern as shown in FIG. 33A during formation of the i-type layerby microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Also, the distribution in the layer thickness direction of N atoms and Oatoms in the i-type layer of the photovoltaic element was analyzed usinga secondary mass spectrometer. The results are shown in FIG. 33B. Fromthe above results, the effects of the present invention have beenevidenced.

Example 12

A photovoltaic element was fabricated (Element No. Example 12) byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions asElement No. Example 1-5, except that the flow rates of SiH₄ gas and GeH₄gas were regulated by mass flow controllers 1021, 1026 in accordancewith the flow patterns as shown in FIG. 34 during formation of thei-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and durability characteristic weremeasured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5, whereby the effects ofthe present invention were evidenced.

Example 13

A photovoltaic element was fabricated (Element No. Example 13) byforming a reflective layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Example 9, except that the RF bias power source 1011 was set at 250mW/cm³, and the DC bias was set via a coil at 50 V for application tothe bias rod 1012 during formation of the i-type layer by microwaveplasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as int Example 9, andthe results were equivalent to those of Example 9, whereby the effectsof the present invention were evidenced.

Example 14

A photovoltaic element was fabricated. (Element No. Example 14) byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 1-5 in Example 1, except that a cylinder of D₂gas (not shown) was used instead of H₂ at a flow rate of 300 sccm duringformation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that Datoms were contained in the i-type layer, whereby the effects of thepresent invention were evidenced.

Example 15

A photovoltaic element was fabricated (Element No. Example 15) byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 1-5 in Example 1, except that the DC bias frombias power source 1011 was changed at a constant rate from 50 V to 80 Vat the same time when the shutter 1013 was opened during formation ofthe n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 1-5, whereby the effects ofthe present invention were evidenced.

Example 16

Using an RF plasma CVD apparatus as shown in FIG. 19, an n-type layerand a p-type layer of a photovoltaic element of the present inventionwere fabricated in accordance with the same procedures as that for thei-type layer formed by RF plasma CVD of Example 1.

In the figure, 1104 is a substrate similar to that used in Example 1.The gas cylinders 1071 to 1079 as shown in the figure each were filledwith the same source gases as in Example 1, each gas being introducedinto a mass flow controller 1021 to 1029 with the same operationprocedure as in Example 1.

After preparation for film formation was completed in the above way, then-type layer was formed on the substrate 1104.

To make the n-type layer, the substrate 1104 was heated to 350° C. bythe heater 1105, the outflow valves 1042, 1044, 1045 and the auxiliaryvalve 1108 were gradually opened to flow H₂ gas, PH₃ (1%)/H₂ gas, andSi₂ H₆ gas through the gas introducing pipe 1103 into the depositionchamber 1101. The inflow rates of the gases were regulated by mass flowcontrollers 1022, 1024, 1025 so that the H₂ gas flow, PH₃ (1%)/H₂ gasflow and Si₂ H₆ gas flow were 50 sccm, 5 sccm, and 3 sccm. The openingof conductance valve 1107 was adjusted by referring to the vacuum gauge1106 so that the pressure within the deposition chamber 1101 was 1 Torr.

Thereafter, the output power of RF power source 1111 was set at 120mW/cm², and RF electric power was introduced through the RF matching box1112 into the cathode 1102 to excite an RF glow discharge to startformation of the n-type layer on the substrate 1104. Upon depositing then-type layer to a thickness of 10 nm, the RF glow discharge was stopped,and the outflow valves 1042, 1044, 1045 and the auxiliary valve 1008were closed to stop the gas inflow into the deposition chamber 1101,whereby the formation of the n-type layer was completed.

Then, the substrate 1004 having the n-type layer deposited thereon wastaken out from the deposition chamber 1101, and installed in thedeposition apparatus 1000 with the microwave glow dischargedecomposition method as used in Example 1, where an i-type layer formedby microwave plasma CVD was deposited on the n-type layer under the sameconditions as those of Element No. Example 1-5 in Example 1.

Then, the substrate 1004 having the i-type layer formed by microwaveplasma CVD thereon was taken out from the deposition chamber 1000, andinstalled in the RF plasma CVD deposition apparatus 1100, as previouslydescribed, where an i-type layer formed by RF plasma CVD was depositedon the i-type layer formed by microwave plasma CVD under the sameconditions as those of Element No. Example 1-5 in Example 1.

Subsequently, a p-type layer was deposited on the i-type by RF plasmaCVD. To make the p-type layer, the substrate 1104 was heated to 200° C.by the heater 1105, the outflow valves 1041 to 1043 and the auxiliaryvalve 1108 were gradually opened to flow SiH₄ gas, H₂ gas, and BF₃(1%)/H₂ gas through the gas introducing tube 1103 into the depositionchamber 1101. Then, the inflow rates were regulated by mass flowcontrollers 1021 to 1023 so that the SiH₄ gas flow, H₂ gas flow, and BF₃(1%)/H₂ gas flow were 0.5 sccm, 100 sccm, and 1 sccm. The opening ofconductance valve 1107 was adjusted by referring to the vacuum gauge1106 so that the pressure within the deposition chamber 1101 was 1 Torr.

Thereafter, the output power of RF power source 1111 was set at 2 mW/cm²and RF electric power was introduced through the RF matching box 1112 tothe cathode 1102 to excite an RF glow discharge to start the formationof the p-type layer on the i-type layer. Upon deposition the p-typelayer to thickness of 5 nm, the RF glow discharge was stopped, and theoutflow valves 1041 to 1043 and the auxiliary valve 1108 were closed tostop the gas inflow into the deposition chamber 1101, whereby theformation of the p-type layer was completed.

Next, on the p-type layer, a transparent electrode and a collectorelectrode were vapor deposited in vacuum to fabricate a photovoltaicelement (Cell No. Example 16). The fabrication conditions for thephotovoltaic element as described above are listed in Table 12.

Comparative Example 3

A photovoltaic element was fabricated (Element No. Comparative Example3) by forming a reflective layer, a transparent conductive layer, ann-type layer, an i-type layer, a p-type layer, a transparent electrode,and a collector electrode on the substrate under the same conditions asthose of Example 16, except that the i-type layer formed by the RFplasma CVD was not made.

For the photovoltaic elements thus fabricated (Element No. Example 16and Element No. Comparative Example 3), the initial characteristics, thelow illuminance characteristic, and the durability characteristic weremeasured as in Example 1. From the measurements, it was determined thatthe photovoltaic element of Element No. Example 16 was superior toElement No. Comparative Example 3, such that the open-circuit voltageand the fill factor of the initial characteristics, the photoelectricconversion efficiency of the low illuminance characteristic, and thedecrease in the photoelectric conversion efficiency (the durabilitycharacteristic) were 1.03 times, 1.04 times, 1.09 times, and 1.07 timesbetter, respectively. Thus, the effects of the present invention wereevidenced.

Example 17

A photovoltaic element was fabricated (Element No. Example 17) byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on the substrate underthe same conditions as listed in Table 13, with the same method as inExample 1.

Comparative Example 4

A photovoltaic element was fabricated (Element No. Example 4) by forminga reflecting layer, a reflection multiplying layer, a first n-typelayer, a first i-type layer, a first p-type layer, a second n-typelayer, a second i-type layer, a second p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as listed in Table 17, except that the first i-type layerformed by RF plasma CVD was not made.

For the photovoltaic elements thus fabricated (Element No. Example 17and Comparative Example 4) in the above manner, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured as in Example 1. From the measurements, ithas been determined that the photovoltaic element of Element No. Example17 was superior to that of Element No. Comparative Example 4, such thatthe open-circuit voltage and the fill factor of the initialcharacteristics, the photoelectric conversion efficiency of the lowilluminance characteristic, and the decrease in the photoelectricconversion efficiency (the durability characteristic) were 1.04 times,1.03 times, 1.06 times and 1.10 times better, respectively. Thus, theeffects of the present invention were evidenced.

Example 18

A photovoltaic element was fabricated (Element No. Example 18 by forminga reflecting layer, a reflection multiplying layer, a first n-typelayer, a first i-type layer, a first p-type layer, a second n-typelayer, a second i-type layer, a second p-type layer, a third n-typelayer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as listed in Table 14, with the same method as in Example 1.

Comparative Example 5

A photovoltaic element was fabricated (Element No. Comparative Example5) by forming a reflecting layer, a reflection multiplying layer, afirst n-type layer, a first i-type layer, a first type p-layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on the substrate under theconditions of Table 17, except that the i-type layers formed by RFplasma CVD were not made.

For the photovoltaic elements thus fabricated (Element No. Example 18and Comparative Example 5), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1. From the measurements, ithas been determined that the photovoltaic element of Element No. Example18 was superior to that of Element No. Comparative Example 5, such thatthe open-circuit voltage and the fill factor of the initialcharacteristics, the photoelectric conversion efficiency of the lowilluminance characteristic, and the decrease in the photoelectricconversion efficiency (the durability characteristic) were 1.03 times,1.02 times and 1.07 times better, respectively. Thus, the effects of thepresent invention were evidenced.

Example 19

Using a multiple chamber separation-type deposition apparatus as shownin FIG. 20, a photovoltaic element of the present invention wasfabricated. In the figure, 1201 and 1209 are a load chamber and anunload chamber, respectively, 1202, 1204, 1205, 1206, and 1208 aredeposition chambers for the layers formed by RF plasma CVD as in Example16, 1203 and 1207 are deposition chambers for the layers formed bymicrowave plasma CVD as in Example 1, 1211 to 1218 are gate valves forseparating one chamber from the other, 1221, 1223 to 1225 and 1227 arecathode electrodes, and 1222 and 1226 are a waveguide portion formicrowaves and a dielectric window, respectively.

First, the substrate was installed in the load chamber 1201, and theload chamber was evacuated of air. Thereafter, gate valve 1211 wasopened, the substrate was moved to first n-type layer deposition chamber1202, and gate valve 1211 was closed. Next, the first n-type layer wasmade on the substrate under the same conditions as those of the firstn-type layer of Example 17. Then, gate valve 1212 was opened, thesubstrate was moved to a first microwave plasma CVD i-type layerdeposition chamber 1203, and gate valve 1212 was closed. Next, a firsti-type layer formed by microwave plasma CVD was deposited on the firstn-type layer under the same conditions as those of the first i-typelayer formed by microwave plasma CVD of Example 17. Next, gate valve1213 was opened, the substrate was moved to first RF plasma CVD, i-typelayer deposition chamber 1204 and gate valve 1213 was closed. Next, afirst i-type layer formed by RF plasma CVD was deposited on the firsti-type layer formed by microwave plasma CVD under the same conditions asthose of the first i-type layer by RF plasma CVD of Example 17.

Gate valve 1214 was then opened, the substrate moved to first p-typelayer deposition chamber 1205, and gate valve 1214 was closed. Next, afirst p-type layer was formed on the first i-type layer by RF plasma CVDunder the same conditions as those of the first p-type layer of Example17. Then, gate valve 1215 was opened, the substrate was moved to asecond n-type layer deposition chamber 1206, and gate valve 1215 wasclosed. Next, a second n-type layer was formed on the first p-type layerunder the same conditions as those of the second n-type layer of Example17. Next, gate valve 1216 was opened, the substrate was moved to secondi-type layer deposit in chamber 1207, and gate valve 1216 was closed.Next, a second i-type layer was formed on the second n-type layer underthe same conditions as those of the second i-type layer of Example 17.Next, gate valve 1217 was opened, the substrate was moved to secondp-type layer deposition chamber 1208, and gate valve 1217 was closed.Next, a second p-type layer was formed on the second i-type layer underthe same conditions as those of the second p-type layer of Example 17.Then, gate valve 1218 was opened, the substrate was moved to unloadcheer 1209, and gate valve 1218 was closed. Then, the substrate wastaken out from the unload chamber 1209, whereby the fabrication of aphotovoltaic element was completed (Element No. Example 19).

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic and the durability characteristicwere measured as in Example 1. From the measurements, it has beendetermined that the photovoltaic element was superior to that of ElementNo. Example 17, such that the open-circuit voltage and the fill factorof the initial characteristics, the photoelectric conversion efficiencyof the low illuminance characteristic, and the decrease in thephotoelectric conversion efficiency (the durability characteristic) were1.01 times, 1.02 times, 1.03 times and 1.01 times better, respectively.Thus, it has been found that a photovoltaic element of the presentinvention can exhibit improved characteristics by fabricating it in themultiple cheer separation-type deposition chamber.

Example 20

A photovoltaic element was fabricated under the same conditions as thoseof Example 17, and using the photovoltaic element, a solar cell modulewas fabricated for use in a car-mounted ventilation fan having a circuitconfiguration as shown in FIG. 28. In FIG. 28, the electric powergenerated by the solar cell module 9101, which is bonded to the bonnetof car, is charged through a reverse-current preventing diode 9102 intoa secondary cell 9104. 9103 is an overcharge preventing diode. Theelectric power from the solar cell module 9101 and the secondary cell9104 is supplied to a motor 9105 for the ventilation fan.

Comparative Example 6

As a comparative example, a photovoltaic element was fabricated underthe same conditions as those of Comparative Example 4, and a car-mountedventilation fan similar to that of Example 21 was made using thephotovoltaic element.

A car which has mounted thereon the ventilation fans as fabricated inExample 20 and Comparative Example 4 was left in an idling state withthe engine running for 168 hours, and then left in sunny weather withthe ventilation fan operating and with the engine stopped, whereafterthe temperature within the car was measured.

As a result, the car-mounted cooling fan of Example 20 achieved aninterior temperature three degrees lower than the car-mounted coolingfan of the comparative example, whereby the effect of the powergeneration system of the present invention was demonstrated.

Example 21

In this example, a photovoltaic element having a laminated p-type layerwas fabricated.

In a source gas supply unit 1020 as shown in FIGS. 18 and 19, the BF₃(1%)/H₂ gas cylinder was replaced with a cylinder of B₂ H₆ gas dilutedto 10% with H₂ gas (B₂ H₆ (10%)/H₂ gas).

On a SUS substrate, a reflecting layer, a reflection multiplying layer,an n-type layer, an i-type layer formed by microwave plasma CVD, and ani-type layer formed by RF plasma CVD were deposited as in Example 1, andsubsequently a p-type layer was formed in the following manner.

After the formation of the i-type layer by RF plasma CVD, the substratewas installed in a microwave plasma CVD apparatus as shown in FIG. 18 toform laminated p-type layer with a doping layer A and a doping layer B.

To make a doping layer B1, the substrate 1004 was heated to 300° C. bythe heater 1005, the outflow valves 1041, 1042, 1047 and the auxiliaryvalve 1008 were gradually opened to flow SiH₄ gas, H₂ gas, and BF₃ /H₂gas through the gas introducing pipe 1003 into the deposition chamber1001. The inflow rates of the gases were regulated by mass flowcontrollers 1021, 1022, 1027 so that the SiH₄ gas flow, the H₂ gas flow,and the BF₃ /H₂ gas flow were 1 sccm, 300 sccm, and 2 sccm. The pressurewithin the deposition chamber 1101 was set to 1 Torr by adjusting theopening of conductance valve 1007 while referring to the vacuum gauge1006.

Thereafter, the output power of the microwave power source (not shown),was set at 50 mW/cm³ and microwave electric power was introduced througha waveguide (not shown), waveguide portion 1010, and dielectric window1002 into deposition chamber 1001 to excite a microwave glow dischargeto start the formation of the doping layer B1 on the i-type layer byopening the shutter 1013. Upon depositing doping layer B1 to a thicknessof 0.5 nm, shutter 1013 was closed, the microwave glow discharge wasstopped, and outflow valves 1041, 1042, 1047 and auxiliary valve 1008were closed to stop the gas inflow into the deposition chamber 1001.

To make doping layer A, the substrate 1004 was heated to 300° C. by theheater 1005, the outflow valve 1043 and the auxiliary valve 1008 weregradually opened to flow B₂ H₆ (10%)/H₂ gas through the gas introducingpipe 1003 into the deposition cheer 1001. The inflow rate of the gas wasregulated by mass flow controller 1023 so that the B₂ H₆ (10%)/H₂ gasflow was 100 sccm. The pressure within the deposition chamber 1001 wasset to 30 mTorr by adjusting the opening of conductance valve 1007 whilereferring to the vacuum gauge 1006.

Thereafter, the output power of the microwave power source (not shown)was set at 50 mW/cm³, and microwave electric power was introducedthrough a waveguide (not shown), the waveguide portion 1010, and thedielectric window 1002 into the deposition chamber 1001 to excite amicrowave glow discharge to start formation of doping layer A on dopinglayer B1 by opening the shutter 1013. Upon depositing doping layer A toa thickness of 0.3 nm, the shutter 1013 was closed, the microwave glowdischarge was stopped, and the outflow valve 1043 and the auxiliaryvalve 1008 was closed to stop the gas inflow into the deposition chamber1001.

Next, doping layer B2 was formed on doping layer A under the sameconditions as those of doping layer B1, except that the layer thicknesswas 10 nm.

Subsequently, on the p-type layer, a 70 μm-thick ITO (In₂ O₃ +SnO₂) thinfilm as the transparent electrode and a 2 μm-thick aluminum (Al) thinfilm as the collector electrode were vapor deposited in vacuum tofabricate photovoltaic elements (Element No. Examples 1-1 to 1-7 andComparative Example 7-1). The fabrication conditions for thephotovoltaic elements as described above are listed in Table 15.

The initial characteristics, low illuminance characteristic, anddurability characteristic were measured for the thus fabricatedphotovoltaic elements (Element No. Examples 21-1 to 21-7 and ComparativeExample 7-1). The results are listed in Table 16.

From Table 16, it is seen that a photovoltaic element with bettercharacteristics is obtained by forming the i-type layer by microwaveplasma CVD within the deposition chamber at a pressure of 50 mTorr orless.

Next, photovoltaic elements were fabricated (Element No. Examples 21-8to 21-10 and Comparative Examples 7-2 to 7-3) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode and a collector electrode on thesubstrate under the same conditions as those of Element No. Example21-5, except that the output power of microwave electric power sourcewas as indicated in Table 17 in making the i-type layer by microwaveplasma CVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 1. Theresults are listed in Table 17. From Table 17, it is seen that aphotovoltaic element having better characteristics can be obtained bydecomposing the source gas with a lower microwave energy than thatnecessary to decompose 100% of the source gas.

Then, photovoltaic elements were fabricated (Element Nos. Examples 21-11to 21-14 and Comparative Example 7-4) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on thesubstrate under the same conditions as those of Element No. Example21-5, except that the RF bias was as indicated in Table 18 duringdeposition of the i-type layer by microwave plasma CVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 1. Theresults are listed in Table 18. From Table 18, it is seen that aphotovoltaic element having excellent characteristics can be obtained byapply a higher RF energy to the source gas than the microwave energy.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 7-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of Element No. Example 21-5, except that SiH₄ gasflow and GeH₄ gas flow were regulated by the mass flow controllers 1021,1026 in accordance with the flow patterns as shown in FIG. 23B duringdeposition of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. The results indicatedthat the open-circuit voltage and the fill factor in the initialcharacteristics, the photoelectric conversion efficiency in the lowilluminance characteristic and the decrease in the photoelectricconversion efficiency (the durability characteristic) in Element No.Example 21-5 were 1.03 times, 1.02 times, 1.08 times and 1.07 timesbetter, respectively, than those in Element No. Comparative Example 7-5.

Also, the variation in the bandgap in the direction of layer thicknessof the i-type layer was examined, whereby it was found that thephotovoltaic element in Element No. Example 21-5 has the minimum valueof bandgap at a position shifted toward the interface between the p-typelayer and the i-type layer, away from the central position of the i-typelayer, while the photovoltaic element in Element No. Comparative Example7-5 has the minimum value of bandgap at a position shifted toward theinterface between the n-type layer and the i-type layer, away from thecentral position of the i-type layer.

Then, photovoltaic elements were fabricated (Element No. Examples 21-15to 21-19 and Comparative Example 7-6) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on thesubstrate under the same conditions as those of the photovoltaic elementof Element No. Example 21-5, except that SiH₄ gas flow and RF dischargeelectric power were as indicated in Table 19 during formation of thei-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 21-5. Theresults are listed in Table 19. As seen in Table 19, a photovoltaicelement having better characteristics can be obtained by depositing thei-type layer formed by RF plasma CVD at a deposition rate of 2 nm/sec orless.

Then, photovoltaic elements were fabricated (Element No. Examples 21-20to 21-22 and Comparative Examples 7-7 to 7-8) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode onthe substrate under the same conditions as those of Element No. Example21-5, except that the thickness of the i-type layer formed by RF plasmaCVD was as indicated in Table 20.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 21-5. Theresults are listed in Table 20. As will be seen from Table 20, aphotovoltaic element having better characteristics can be obtained bymaking the thickness of the i-type layer formed by RF plasma CVD to be30 nm or less (Element No. Examples 21-20 to 21-22).

Then, photovoltaic elements were fabricated (Element No. Examples 21-23to 21-26) by forming a reflecting layer, a reflection multiplying layer,an n-type layer, an i-type layer a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of the photovoltaic element of Element No. Example21-5, except that the RF electric power was as indicated in Table 21during formation of the i-type layer by RF plasma CVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Element No.Example 21-5. The results are listed in Table 21. As will be seen fromTable 21, a photovoltaic element having better characteristics can beobtained when the value of the half width of a peak at 2000 cm⁻¹ in theinfrared absorption spectrum divided by the peak height is greater inthe i-type layer formed by microwave plasma CVD than in the i-type layerformed by RF plasma CVD.

Then, a photovoltaic element was fabricated (Element No. Example 21-27)by forming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions asElement No. Example 21-5, except that doping layer A was not formed inmaking the p-type layer.

For the thus fabricated photovoltaic element, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 1. Theresults indicated that the open-circuit voltage and the fill factor ofthe initial characteristics, the photoelectric conversion efficiency ofthe low illuminance characteristic, and the decrease in thephotoelectric conversion efficiency (the durability characteristic) inElement No. Example 21-5 were 1.02 times, 1.03 times, 1.07 times and1.08 times better, respectively, than those in Element No. Example21-27.

From the above results, it is seen that the photovoltaic elements(Element No. Examples 21-1 to 21-26) of the present invention exhibitbetter characteristics than conventional photovoltaic elements. Thephotovoltaic elements of the present invention have been fabricated suchthat an i-type layer formed by microwave plasma CVD is deposited at aninternal pressure of 50 mTorr or less by applying a lower microwaveenergy and a higher RF energy than the microwave energy necessary todecompose 100% of the source gas, and an i-type layer formed by RFplasma CVD is deposited to a thickness of 30 nm or less on the p-typelayer at a deposition rate of 2 nm/sec. The bandgap smoothly changes inthe direction of layer thickness, and the minimum value of bandgap is ata position shifted toward the interface between the p-type layer and thei-type layer, away from the central position of the i-type layer. Thep-type layer and/or the n-type layer has a laminated structurecomprising a layer composed of a Group III and/or a Group V element asthe main constituent, and a layer containing a valence electron controlagent and silicon atoms as the main constituent. Thus, the effects ofthe present invention have been evidenced.

Example 22

Photovoltaic elements (Element No. Examples 22-1 to 22-8) werefabricated to form a reflecting layer, a reflection multiplying layer,an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of Element No. Example 21-5 in Example 21, exceptthat the SiH₄ gas flow and GeH₄ gas flow were regulated by mass flowcontrollers 1021, 1026 in accordance with the flow patterns as shown inFIG. 23A, and as conducted in Example 21. The SiH₄ gas flow wasmaintained at 200 sccm and the GeH₄ gas flow at 1 sccm, and the regionof the maximum bandgap has a layer thickness as indicated in Table 22during formation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21. The results arelisted in Table 22. As will be seen from Table 22, the photovoltaicelements (Element Nos. Examples 22-1 to 22-7) having a layer thicknessof 1 to 30 nm in the region of the maximum bandgap exhibit bettercharacteristics, whereby the effects of the present invention aredemonstrated.

Example 23

A photovoltaic element (Element No. Example 23) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 21-5 in Example 1, except that the BF₃ (2000pm)/H₂ gas flow and PH₃ (2000 ppm)/H₂ gas flow were 0.4 sccm and 0.02sccm, using cylinder 1077 and cylinder 1078, respectively, duringdeposition of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 21, and the resultswere equivalent to those of Element No. Example 21-5.

Example 24

A photovoltaic element (Element No. Example 24) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof the element in Example 23, except for using a cylinder of AsH₃ /H₂gas instead of PH₃ (2000 ppm)/H₂ gas at a flow rate of 0.01 sccm duringdeposition of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 23, and the results wereequivalent to those of Element No. Example 23.

Example 25

A photovoltaic element (Element No. Example 25) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions asElement No. Example 21-5, except for using a cylinder of NO/He gas 1079at a flow rate of 0.5 sccm for the i-type layer formed by microwaveplasma CVD and at 0.05 sccm for the i-type layer formed by RF plasmaCVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5.

Also, composition analysis of the photovoltaic element in Example 25 wasperformed using a secondary ion mass spectrometer, and it was confirmedthat oxygen atoms and nitrogen atoms were contained in the i-type layer.

The effects of the present invention thus have been demonstrated fromthe above results.

Example 26

A photovoltaic element (Element No. Example 26) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 21-5, except for using a cylinder of Si₂ H₆ gasat a flow rate of 40 sccm, regulated by a mass flow controller 1021 inaccordance with a flow pattern as shown in FIG. 25A, during depositionof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5.

Also, the distribution in the layer thickness direction of Si andhydrogen atoms in the i-type layer of the photovoltaic element wasanalyzed using a secondary ion mass spectrometer, resulting in the sametendency as in FIG. 25B. From the above results, the effects of thepresent invention have been demonstrated.

Example 27

Photovoltaic elements (Element No. Examples 27-1 to 27-5) werefabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Element No. Example 21-5, except that the distance betweenthe mixing point of SiH₄ gas and GeH₄ gas and the deposition chamber1001 in the source gas supply unit 1020 was set as indicated in Table23.

For the photovoltaic elements thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 21. Theresults are listed in Table 23. As will be seen from Table 17, by makingthe distance between the mixing point of SiH₄ gas and GeH₄ gas and thedeposition chamber 1001 5 m or less, a photovoltaic element havingfurther improved characteristics can be obtained.

Example 28

A photovoltaic element was fabricated under the same conditions asElement No. Example 21-5, and using this photovoltaic element, a solarcell module was fabricated and used as a power source for an analogclock with a circuit configuration as shown in FIG. 28.

Comparative Example 8

As a comparative example, a photovoltaic element was fabricated underthe same conditions as Element No. Comparative Example 7-7. Using thisphotovoltaic element, the same analog clock as in Example 28 was made.

The analog clocks as fabricated in Example 28 and Comparative Example 8were installed on the wall of a room, and an indoor lamp was lit for 8.5hours a day. As a result, the analog clock of Example 28 worked theentire day, but the analog clock of the comparative example did not workthe entire day, whereby the effects of the power generation system ofthe present invention were evidenced.

Example 29

A photovoltaic element (Element No. Example 29) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except that the flow rates of SiH₄ gas andGeH₄ gas were regulated by mass flow controllers 1021, 1026 inaccordance with the flow pattern shown in FIG. 26 during formation ofthe i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5, whereby the effects ofthe present invention were demonstrated.

Example 30

A photovoltaic element (Element No. Example 30) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions asElement No. Example 21-5, except for using a cylinder of B₂ H₆ (2000ppm)/H₂ gas at a flow rate of 0.5 sccm during formation of the i-typelayer by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to Element No. Example 21-5, whereby the effects of thepresent invention were demonstrated.

Example 31

A photovoltaic element (Element No. Example 31) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except that the flow rate of NO/He gas wasregulated by a mass flow controller 1029 in accordance with the flowpattern shown in FIG. 33A, during formation of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5.

Also, the distribution in the layer thickness direction of N atoms and Oatoms in the i-type layer of the photovoltaic element was analyzed usinga secondary ion mass spectrometer, resulting in the same tendency asindicated in FIG. 33B. From the above results, the effects of thepresent invention were demonstrated.

Example 32

A photovoltaic element (Element No. Example 32) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except that the flow rates of SiH₄ gas andGeH₄ gas were regulated by mass flow controllers 1021, 1026 inaccordance with the flow patterns as shown in FIG. 34, during formationof the i-type layer by microwave plasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic and the durabilitycharacteristic were measured in the same manner as in the Example 21,and the results were equivalent to those of Element No. Example 21-5,whereby the effects of the present invention were evidenced.

Example 33

Photovoltaic elements (Element No. Examples 33-1 to 33-5) werefabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on substrates under the sameconditions as Element No. Example 21-5, except that the layer thicknessof doping layer A was as indicated in Table 24, during formation of thep-type layer.

For the photovoltaic elements thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 21. Theresults are listed in Table 24. As will be seen from Table 24, thephotovoltaic elements (Element No. Examples 33-1 to 33-4) having a layerthickness of the doping layer of 0.01 to 1 nm exhibit improvedcharacteristics, whereby the effects of the present invention aredemonstrated.

Example 34

A photovoltaic element (Element No. Example 34) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 21-5, except that doping layer A and doping layer B wereformed under the conditions of Table 25, during formation of the n-typelayer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5 whereby the effects ofthe present invention were demonstrated.

Example 35

A photovoltaic element (Element No. Example 35) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except that doping layer A and doping layer Bwere formed under the conditions indicated in Table 26, during formationof the p-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to Element No. Example 21-5, whereby the effects of thepresent invention were evidenced.

Example 36

A photovoltaic element (Element No. Example 36) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofExample 29, except that the power output of the bias power source 1011was set at 250 mW/cm³, and the DC bias was set via a coil at 50 V forapplication to the bias rod 1012 during formation of the i-type layer bymicrowave plasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 29, andthe results were equivalent to those of Example 29, whereby the effectsof the present invention were evidenced.

Example 37

A photovoltaic element (Element No. Example 37) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except for using a cylinder of D₂ gas (notshown) instead of a H₂ gas at a flow rate of 300 sccm during formationof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to those of Element No. Example 21-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that Datoms were contained in the i-type layer, whereby the effects of thepresent invention were evidenced.

Example 38

A photovoltaic element (Element No. Example 38) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 21-5, except that the DC bias of bias power source1011 was changed at a constant rate from 50 V to 80 V when the shutter1013 was opened during formation of the n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 21, and the results wereequivalent to Element No. Example 21-5, whereby the effects of thepresent invention were evidenced.

Example 39

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Example 21-5, except for forming the n-type layer and thep-type layer using a deposition apparatus employing the RF plasma CVDmethod as shown in FIG. 19.

To make the n-type layer, the substrate 1104 was heated to 350° C. bythe heater 1105, the outflow valves 1042, 1044, 1045 and the auxiliaryvalve 1108 were gradually opened to flow H₂ gas, PH₃ (1%)/H₂ gas and Si₂H₆ gas through the gas introducing pipe 1103 into the deposition chamber1101. The inflow rates of the gases were regulated by mass flowcontrollers 1022, 1024, 1025 so that the H₂ gas flow, the PH₃ (1%)/H₂gas flow, and the Si₂ H₆ gas flow were 50 sccm, 5 sccm, and 3 sccm. Thepressure within the deposition chamber 1101 was set to 1 Torr byadjusting the opening of conductance valve 1107 while referring to thevacuum gauge 1106.

Thereafter, the output power of RF power source 1111 was set at 120mW/cm² and it was introduced through the RF matching box 1112 to thecathode 1102 to excite an RF glow discharge to start the formation ofthe n-type layer on the substrate 1104. Upon forming an n-type layerhaving a thickness of 10 nm, the RF flow discharge was stopped, and theoutflow valves 1042, 1044, 1045 and the auxiliary valve 1108 were closedto stop the gas inflow into the deposition chamber 1101, whereby theformation of the n-type layer was completed.

Then, the substrate 1004 having the n-type layer formed thereon wastaken out from the deposition chamber 1101, and installed in themicrowave plasma CVD deposition apparatus 1000 as with Element No.Example 21-5, where an i-type layer formed by microwave plasma CVD wasdeposited on the n-type layer under the same conditions as those ofElement No. Example 21-5.

Then, the substrate 1004 having the i-type layer formed thereon wastaken out from the deposition chamber 1000, and installed in the RFplasma CVD deposition apparatus 1100 as previously described, where ani-type layer formed by RF plasma CVD was deposited on the i-type layerformed by microwave plasma CVD under the same conditions as those ofElement No. Example 21-5.

Subsequently, a p-type layer having a doping layer A and a doping layerB laminated together was formed on the i-type layer formed by RF plasmaCVD.

To form doping layer BI, the substrate 1104 was heated to 200° C. by theheater 1105, the outflow valves 1041, 1042, 1047 and the auxiliary valve1108 were gradually opened to flow SiH₄ gas, H₂ gas, and BF₃ (2000ppm)/H₂ gas through the gas introducing tube 1103 into the depositionchamber 1101. The inflow rates of these gases were regulated by massflow controllers 1021, 1022, 1027 so that the SiH₄ gas flow, H₂ gasflow, and BF₃ (2000 ppm)/H₂ gas flow were 0.03 sccm, 100 sccm, and 1sccm. The pressure within the deposition chamber 1101 was set to 1 Torrby adjusting the conductance valve 1107 while referring to the vacuumgauge 1106.

Thereafter, the output power of RF power source 1111 was set at 2 W/cm²,and RF electric power was introduced through the RF matching box 1112 tothe cathode 1102 to excite an RF glow discharge to start the formationof doping layer B1 on the i-type layer by RF plasma CVD. Upon depositingdoping layer B1 having a thickness of 0.3 nm, the RF glow discharge wasstopped, and the outflow valves 1041, 1042, 1047 and the auxiliary valve1108 were closed to stop the gas inflow into the deposition chamber1101.

Then, to form doping layer A, the substrate 1104 was heated to 200° C.by the heater 1105, and the outflow valve 1043 and the auxiliary valve1108 were gradually opened to flow B₂ H₆ (10%)/H₂ gas through the gasintroducing tube 1103 into the deposition chamber 1101. The inflow rateof the gas was regulated by a mass flow controller 1023 so that the B₂H₆ (10%)/H₂ gas flow was 50 sccm. The pressure within the depositionchamber 1101 was set to 1 Torr by adjusting the conductance valve 1107while referring to the vacuum gauge 1106.

Thereafter, the output power of RF power source 1111 was set at 3 W/cm²,and RF electric power was introduced through the RF matching box 1112into the cathode 1102 to excite an RF glow discharge to start theformation of doping layer A on doping layer B1. Upon forming dopinglayer A having a thickness of 0.1 nm, the RF glow discharge was stopped,and the outflow valve 1048 and the auxiliary valve 1108 were closed tostop the gas inflow into the deposition chamber 1101.

Next, doping layer B2 was formed on doping layer A under the sameconditions as doping layer B1, except that the SiH₄ gas flow and the BF₃/H₂ gas flow were 0.5 sccm and 10 sccm and the layer thickness was 5 nm.

Next, a transparent electrode and a collector electrode were vapordeposited on the p-type layer, whereby a photovoltaic element (Cell No.Example 39) was fabricated. The fabrication conditions for thephotovoltaic element as described above are listed in Table 27.

Comparative Example 9

A photovoltaic element (Element No. Comparative Example 9) wasfabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of Example 39, except that the i-type layer formedby RF plasma CVD was not deposited.

For the photovoltaic elements thus fabricated (Element No. Example 39and Comparative Example 9), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 21. From the measurements, itwas determined that the photovoltaic element of Element No. Example 39was superior to Comparative Example 9, in that the open-circuit voltageand the fill factor of the initial characteristics, the photoelectricconversion efficiency of the low illuminance characteristic, and thedecrease in the photoelectric conversion efficiency (the durabilitycharacteristic) were 1.03 times, 1.04 times, 1.09 times, and 1.07 timesbetter, respectively, whereby the effects of the present invention weredemonstrated.

Example 40

A photovoltaic element (Element No. Example 40) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as listed in Table 28, with the same method as inExample 21.

Comparative Example 10

A photovoltaic element (Element No. Comparative Example 10) wasfabricated by forming a reflecting layer, a reflection multiplyinglayer, a first n-type layer, a first i-type layer, a first p-type layer,a second n-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as in Example 40, except that the first i-type layerformed by RF plasma CVD was not deposited.

For the photovoltaic elements thus fabricated (Element No. Example 40and Comparative Example 10), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 21. From the measurements, itwas determined that the photovoltaic element of Element No. Example 40was superior to Comparative Example 10, in that the open-circuit voltageand the fill factor of the initial characteristics, the photoelectricconversion efficiency of the low illuminance characteristic, and thedecrease in the photoelectric conversion efficiency (the durabilitycharacteristic) were 1.03 times, 1.03 times, 1.07 times, and 1.06 timesbetter, respectively, whereby the effects of the present invention weredemonstrated.

Example 41

A photovoltaic element (Element No. Example 41) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as listed in Table 29, with the same method as in Example 21.

Comparative Example 11

A photovoltaic element was fabricated (Element No. Comparative Example11) by forming a reflecting layer, a reflection multiplying layer, afirst n-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as in Example 41, except that the first and second RF plasmaCVD i-type layers were not formed.

For the photovoltaic elements thus fabricated (Element No. Example 41and Comparative Example 11), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 21. From the measurements, itwas determined that the photovoltaic element of Element No. Example 41was superior to Comparative Example 11, in that the open-circuit voltageand the fill factor of the initial characteristics, the photoelectricconversion efficiency of the low illuminance characteristic, and thedecrease in the photoelectric conversion efficiency (the durabilitycharacteristic) were 1.03 times, 1.03 times, 1.08 times and 1.07 timesbetter, respectively, whereby the effects of the present invention weredemonstrated.

Example 42

Using a multiple chamber separation-type deposition apparatus as shownin FIG. 21, a photovoltaic element of the present invention wasfabricated. In the figure, 1301 and 1311 are a load chamber and anunload chamber, respectively, 1302, 1304 to 1308 and 1310 are depositionchambers for the layers formed by RF plasma CVD as in Example 39, 1303and 1309 are deposition chambers for the layers formed by microwaveplasma CVD as in Example 21, 1321 to 1330 are gate valves for separatingone chamber from the other, 1341, 1343 to 1347 and 1349 are cathodeelectrodes, and 1342 and 1348 are a waveguide portion for microwaves anda dielectric window, respectively.

First, the substrate was installed in the load chamber 1301, and theload chamber 1301 was evacuated. Thereafter, gate valve 1321 was opened,the substrate was moved to first n-type layer deposition chamber 1302,and the gate valve 1321 was closed. Next, the first n-type layer wasformed on the substrate under the same conditions as those of the firstn-type layer of Example 40. Then gate valve 1322 was opened, thesubstrate was moved to first i-type layer microwave plasma CVDdeposition chamber 1303 and the gate valve 1322 was closed. Next a firsti-type layer formed by microwave plasma CVD was deposited on the firstn-type layer under the same conditions as those of the first i-typelayer formed by microwave plasma CVD of Example 40. Next, gate valve1323 was opened, the substrate was moved to first i-type layer RF plasmaCVD deposition chamber 1304, and the gate valve 1323 was closed. Next, afirst i-type layer formed by RF plasma CVD was deposited on the firstn-type layer under the same conditions as those of the first i-typelayer formed by RF plasma CVD of Example 40.

Gate valve 1324 was then opened, the substrate was moved to first p-typelayer/doping layer B1 deposition chamber 1305, and the gate valve 1324was closed. Next, a first p-type layer/doping layer B1 was formed on thefirst i-type layer formed by RF plasma CVD under the same conditions asthose of the first p-type layer/doping layer B1 of Example 40. Then gatevalve 1325 was opened, the substrate was moved to first p-typelayer/doping layer A deposition chamber 1306, and the gate valve 1325was closed. Next a first p-type layer/doping layer A was formed on thefirst p-type layer/doping layer B1 under the same conditions as those ofthe first p-type layer/doping layer A of Example 40. Next, gate valve1326 was opened, the substrate was moved to first p-type layer/dopinglayer B2 deposition chamber 1307, and the gate valve 1326 was closed.Next, first p-type layer/doping layer B2 was formed on the first p-typelayer/doping layer A under the same conditions as those of the firstp-type layer/doping layer B2 of Example 40. Next, gate valve 1327 wasopened, the substrate was moved to second n-type layer depositionchamber 1308, and the gate valve 1327 was closed. Next, a second n-typelayer was formed on the first p-type layer/doping layer B2 under thesame conditions as those of the second n-type layer of Example 40. Then,gate valve 1328 was opened, the substrate was moved to the second i-typelayer deposition chamber 1309, and the gate valve 1328 was closed. Next,a second i-type layer was formed on the second n-type layer under thesame conditions as those of the second i-type layer of Example 40. Then,gate valve 1329 was opened, the substrate was moved to the second p-typelayer deposition chamber 1310, and the gate valve 1329 was closed. Next,a second p-type layer was made on the second i-type layer under the sameconditions as the second p-type layer of Example 40. The, gate valve1330 was opened, the substrate was moved to unload chamber 1311, andgate valve 1330 was closed. Then, the substrate was taken out fromunload chamber 1311, whereby the fabrication of a photovoltaic elementwas completed (Element No. Example 42).

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 21. Fromthe measurements, it was found that the photovoltaic element of ElementNo. Example 42 was superior to that of Element No. Example 40, in theopen-circuit voltage and the fill factor of the initial characteristics,the photoelectric conversion efficiency of the low illuminancecharacteristic, and the decrease in the photoelectric conversionefficiency (the durability characteristic) were 1.01 times, 1.02 times,1.02 times and 1.02 times better, respectively, whereby it was shownthat a photovoltaic element of the prevent invention can exhibit bettercharacteristics by fabricating it in the multiple chamberseparation-type deposition cheer. Thus, the effects of the presentinvention were evidenced.

Example 43

A photovoltaic element was fabricated under the same conditions as thoseof Example 40, whereby a solar cell module was formed using thephotovoltaic element, and a car-mounted ventilation fan having a circuitconfiguration as shown in FIG. 28 was fabricated.

Comparative Example 11

As a comparative example, a photovoltaic element was fabricated underthe same conditions as those of Comparative Example 10, and acar-mounted ventilation fan similar to that of Example 41 was made usingthe photovoltaic element.

A car which has mounted thereon the car-mounted ventilation fans asfabricated in Example 41 and Comparative Example 11 was left in anidling state with the engine running for 168 hours, and then left insunny weather with the ventilation fan working and with the enginestopped, whereafter the temperature within the car was measured. As aresult, the car-mounted cooling fan of Example 43 achieved an interiortemperature three degrees lower than the car-mounted cooling fan of thecomparative example, whereby the effects of the power generation systemof the present invention were demonstrated.

Example 44

Using a microwave plasma CVD manufacturing apparatus comprising a sourcegas supply unit 1020 and a deposition unit 1000 as shown in FIG. 18 andan RF plasma manufacturing CVD manufacturing apparatus comprising asource gas supply unit 1020 and a deposition unit 1100 as shown in FIG.19, a photovoltaic element of the present invention was fabricated. Inthis example, B and P atoms were doped into the i-type layer formed bymicrowave plasma CVD.

On a substrate, a reflecting layer, a reflection multiplying layer, andan n-type layer were formed under the same conditions as those ofElement No. Example 1-5 of Example 1, and subsequently, the formation ofi-type layers by microwave plasma CVD and RF plasma CVD was performed inthe following manner.

To form an i-type layer by microwave plasma CVD, the substrate 1004 washeated to 350° C. by the heater 1005, the outflow valves 1041, 1042,1046 to 1048 and the auxiliary valve 1008 were gradually opened to flowSiH₄ gas, H₂ gas, GeH₄ gas, BF₃ (2000 ppm)/H₂ gas, and PH₃ (2000 ppm)/H₂gas through a gas introducing pipe 1003 into the deposition chamber. Theinflow rates of the gases were regulated by mass flow controllers 1021,1022, 1026 to 1028 so that the SiH₄ gas flow, H₂ gas flow, GeH₄ gasflow, BF₃ (2000 ppm)/H₂ gas flow, and PH₃ (2000 ppm)/H₂ gas flow were200 sccm, 500 sccm, 1 sccm, 0.2 sccm, and 0.1 sccm. The pressure withinthe deposition chamber 1001 was set as indicated in Table 30 byadjusting the opening of conductance valve 1007 while referring to thevacuum gauge 1006.

Thereafter, shutter 1013 was closed, the output power of a microwavepower source (not shown) was set at 170 mW/cm³, and the microwaves wereintroduced through a waveguide (not shown), the waveguide portion 1010,and the dielectric window 1002 into the deposition chamber 1001 toexcite a microwave glow discharge. Then, the RF bias of bias powersource 1011 was set at 350 mW/cm³, and the DC bias was set via a coil at0 V, and applied to the bias rod 1012. Thereafter, the shutter 1013 wasopened to start fabrication of an i-type layer by microwave plasma CVDon the n-type layer, while at the same time regulating the SiH₄ gas flowin accordance with the flow patterns as indicated in FIG. 23A, by meansof the mass flow controllers 1021, 1026. Upon forming the i-type layerhaving a layer thickness of 300 nm, the shutter 1013 was closed, theoutput of bias power source 1011 was turned off, the microwave glowdischarge was stopped, and the outflow valves 1041, 1042, 1046 and theauxiliary valve 1008 were closed to stop the gas inflow into thedeposition chamber 1001.

Then, the substrate 1004 was taken out from the deposition chamber 1001,and installed in the deposition chamber 1101 of the RF plasma CVDdeposition unit 1100 as shown in FIG. 19, where an i-type layer formedby RF plasma CVD was deposited.

To deposit an i-type layer by RF plasma CVD, the substrate 1104 washeated to 300° C. by the heater 1105, the outflow valves 1041, 1042,1047, 1048 and the auxiliary valve 1008 were gradually opened to flowSiH₄ gas, H₂ gas, BF₃ (2000 ppm)/H₂ gas, and PH₃ (2000 ppm)/H₂ gasthrough the gas introducing tube 1003 into the deposition chamber 1101.The inflow rates of the gases were regulated by mass flow controllers1021, 1022, 1027, 1028 so that the SiH₄ gas flow, H₂ gas flow, BF₃ (2000ppm)/H₂ gas flow, and PH₃ (2000 ppm)/H₂ gas flow were 8 sccm, 100 sccm,0.4 sccm, and 0.02 sccm. The pressure within the deposition chamber 1101was set to 0.5 Torr by adjusting the opening of conductance valve 1007while referring to the vacuum gauge 1006.

Thereafter, the output power of an RF power source 1111 was set at 120mW/cm³, and the RF electric power was introduced through the RF matchingbox 1112 into the cathode 1102 to excite an RF glow discharge to startfabrication of an i-type layer by RF plasma CVD on the i-type layerformed by microwave plasma CVD. Upon making the i-type layer 10 nmthick, the RF glow discharge was stopped, and outflow valves 1041, 1042and auxiliary valve 1008 were closed to stop the gas inflow into thedeposition chamber 1101, whereby the formation of the i-type layer wascompleted.

Then, the substrate 1004 was taken out from the deposition chamber 1101,and installed in the deposition chamber 1001 microwave plasma CVDdeposition unit 1000 as shown in FIG. 18, where a p-type layer wasformed under the same conditions as in Example 1.

Further, on the p-type layer, a 70 μm-thick ITO (In₂ O₃ +SnO₂) thin filmas the transparent electrode and a 2 μm-thick aluminum (Al) thin film asthe collector electrode were vapor deposited in vacuum to fabricate aphotovoltaic element (Element No. Examples 44-1 to 44-7, ComparativeExample 12-1).

The initial characteristics, low illuminance characteristic, anddurability characteristic were measured for the thus fabricatedphotovoltaic elements. The results are listed in Table 30. As will beseen from Table 30, a photovoltaic element having excellentcharacteristics can be fabricated by making the i-type layer bymicrowave plasma CVD under a pressure in the deposition cheer 1001 of 50mTorr or less.

Next, using a substrate of barium borosilicate glass (7059 manufacturedby Corning), an i-type layer formed by microwave plasma CVD wasdeposited on the substrate by opening the shutter 1013 for two minutesunder the same fabrication conditions as the i-type layer formed bymicrowave plasma CVD in Element No. Example 44-5, except that SiH₄ gasflow and GeH₄ gas flow and the microwave power were as indicated inTable 3, whereby the decomposition efficiency of the source gas wasobtained in accordance with the layer thickness, and the same results ofTable 3 were attained.

Then, photovoltaic elements (Element No. Examples 44-8 to 44-10 andComparative Examples 12-2 to 12-3) were fabricated by forming areflecting layer, a reflection multiplying layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on a substrate under the same conditions as those of thephotovoltaic element in Element No. Example 44-5, except that themicrowave power was as indicated in Table 31 during formation of thei-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristic,and the durability characteristic were measured as in Element No.Example 44-5. The results are listed in Table 31. As will be seen fromTable 31, a photovoltaic element having excellent characteristics can beobtained by decomposing the source gas with a lower microwave energythan the microwave energy necessary to decompose 100% of the source gas.

Then, photovoltaic elements (Elements No. Examples 44-11 to 44-14 andComparative Example 12-4) were fabricated by forming a reflecting layer,a reflection multiplying layer, an n-type layer, an i-type layer, ap-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as in Element No. Example 44-5,except that the RF bias was as indicated in Table 32 during formation ofthe i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 44-5. Theresults are listed in Table 32. As is seen from Table 32, a photovoltaicelement having excellent characteristics can be obtained by applying ahigher RF energy to the source gas than the microwave energy.

Next, using a stainless substrate and a barium borosilicate glass (7059manufactured by Corning) substrate, an i-type layer 1 μm thick wasformed on a substrate under the same conditions as the i-type layerformed by microwave plasma CVD in Element No. Example 44-5, except thatthe SiH₄ gas flow and GeH₄ gas flow were as indicated in Table 6,whereby a sample for the measurement of material properties wasfabricated. Further, using a barium borosilicate glass (7059manufactured by Corning) substrate, an i-type layer 1 μm thick wasformed on a substrate under the same conditions as the i-type layerformed by RF plasma CVD in Element No. Example 44-5, whereby a samplefor the measurement of material properties was fabricated.

The bandgap and the composition of the fabricated sample for themeasurement of material properties were determined to obtain therelation between the composition ratio of Si to Ge atoms and thebandgap, and the same results as in Table 6 were obtained.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 12-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example44-5, except that the SiH₄ gas flow and GeH₄ gas flow were regulated bythe mass flow controllers 1021, 1026 in accordance with the flowpatterns as shown in FIG. 23B during deposition of the i-type layer bymicrowave plasma CVD.

For the thus fabricated photovoltaic element, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Element No.Example 44-5. The results indicated that the open-circuit voltage andthe fill factor of the initial characteristics, the low illuminancecharacteristic, and the durability characteristic of Element No. Example44-5 were 1.03 times, 1.03 times, 1.08 times and 1.06 times better,respectively, than those in Element No. Comparative Example 12-5.

Further, the composition analysis in the layer thickness direction ofthe Si atoms and Ge atoms in the i-type layer formed by microwave plasmaCVD in Element No. Example 44-5 and Element No. Comparative Example 12-5was performed in the same manner as the previous composition analysis.It was found that the photovoltaic element in Element No. Example 44-5had a minimum value of bandgap at a position shifted toward theinterface between the p-type layer and the i-type layer away from thecentral position of the i-type layer, while the photovoltaic element inElement No. Comparative Example 12-5 had the minimum value of bandgap ata position shifted toward the interface between the n-type layer and thei-type layer away from the central position of the i-type layer.

For comparison, a photovoltaic element was fabricated (Element No.Example 44-15) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example44-5, except that BF₃ (2000 ppm)/H₂ gas and PH₃ (2000 ppm)/H₂ gas werenot flowed during formation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 44-5. Fromthe results, it was found that the photovoltaic element of Element No.Example 44-5 was superior to that of Element No. Example 44-15, in thatthe open-circuit voltage and the fill factor of the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were 1.03 times, 1.02 times, 1.07 times, and 1.07 timesbetter.

Composition analysis of the photovoltaic element of Element No. Example44-5 was performed using a secondary ion mass spectrometer, confirmingthat B atoms and P atoms were contained in the i-type layer.

Then, photovoltaic elements were fabricated (Element No. Examples 44-16to 44-20 and Comparative Example 12-6) by forming a reflecting layer, areflection multiplying layer, a n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on a substrateunder the same conditions as those of the photovoltaic element inElement No. Example 44-5, except that the SiH₄ gas flow and the RFdischarge electric power were as indicated in Table 33 during depositionof the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 44-5. Theresults are listed in Table 33.

As seen from Table 33, a photovoltaic element having excellentcharacteristics can be fabricated by depositing the i-type layer by RFplasma CVD at a deposition rate of 2 nm/sec or less.

Then, photovoltaic elements were fabricated (Element No. Examples 44-21to 44-23 and Comparative Examples 12-7 to 12-8) by forming a reflectinglayer, a reflection multiplying layer, a n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 44-5, except that the layer thickness of thei-type layer formed by RF plasma CVD was as indicated in Table 34.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 44-5. Theresults are listed in Table 34. As is seen from Table 34, thephotovoltaic elements (Element No. Examples 44-21 to 44-23) providedwith the i-type layer formed by RF plasma CVD having a layer thicknessof 30 nm or less have excellent characteristics.

Then, photovoltaic elements were fabricated (Element No. Examples 44-24to 44-27) by forming a reflecting layer, a reflection multiplying layer,an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example44-5, except that the RF discharge power was as indicated in Table 35during formation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristics, and the durability characteristicwere measured in the same manner as in Element No. Example 44-5. Theresults are listed in Table 35. As is seen from Table 35, thephotovoltaic elements having a greater value of half-width of a peak of2000 cm⁻¹ in the infrared absorption spectrum divided by the height ofthe peak in the i-type layer formed by RF plasma CVD than in the i-typelayer formed by microwave plasma CVD have the better characteristics.

From the above results, it has been found that the photovoltaic elementsof the present invention have better characteristics as compared withconventional photovoltaic elements. The photovoltaic elements of thepresent invention have an i-type layer formed by microwave plasma CVD atan internal pressure of 50 mTorr or less by applying to the source gas alower microwave energy and a higher RF energy than the microwave energynecessary to decompose 100% of the source gas. An i-type layer formed byRF plasma CVD is deposited 30 nm thick or less at a deposition rate of 2nm/sec or less, such that the bandgap smoothly changes in the directionof layer thickness. The minimum value of bandgap is at a positionshifted toward the interface between the p-type layer and the i-typelayer, away from the central position of the i-type layer, wherein thevalence electron control agent serving as a donor and an acceptor isdoped in the i-type layer. Thus, the effects of the present inventionhave been evidenced.

Example 45

Photovoltaic elements (Element No. Examples 45-1 to 45-8) werefabricated in such a manner as to form a reflecting layer, a transparentconductive layer, an n-type layer, an i-type layer, a p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as Element No. Example 44-5, except that after theSiH₄ gas flow and GeH₄ gas flow were regulated by mass flow controllers1021, 1026 in accordance with the flow patterns as shown in FIG. 23A, asconducted in Example 1, the SiH₄ gas flow was maintained at 200 sccm andGeH₄ at 1 sccm. The region of the maximum bandgap was made to have alayer thickness as indicated in Table 36, during formation of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44. The results arelisted in Table 36. As is seen from Table 36, the photovoltaic elements(Element No. Examples 45-1 to 45-7) having a layer thickness of 1 to 30nm in the region of the maximum bandgap according to the presentinvention exhibit better characteristics, whereby the effects of thepresent invention have been evidenced.

Example 46

A photovoltaic element (Element No. Example 46) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. 44-5 in Example 44, except that a cylinder of AsH₃ /H₂gas was used instead of PH₃ (2000 ppm)/H₂ at a flow rate of 0.5 sccm forthe i-type layer formed by microwave plasma CVD, and of 0.1 sccm for thei-type layer formed by RF plasma CVD, during deposition of the i-typelayer by RF plasma CVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 44, and the results wereequivalent to those of Element No. Example 44-5.

Example 47

A photovoltaic element (Element No. Example 47) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 44-5, except that the BF₃ (2000 ppm)/H₂ gas flow and PH₃(2000 ppm)/H₂ gas flow were regulated in accordance with the flowpatterns as shown in FIGS. 41 and 42 by the mass flow controllers 1027,1028 during deposition of the i-type layer formed by microwave plasmaCVD. The BF₃ (2000 ppm)/H₂ gas flow and PH₃ (2000 ppm)/H₂ gas flow were1 sccm and 0.3 sccm during formation of the i-type layer by RF plasmaCVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristics weremeasured in the same manner as in Example 44, and the results wereequivalent to those of Element No. Example 44-5.

Also, the distribution of B and P atoms in the i-type layer of thephotovoltaic element was analyzed using a secondary ion massspectrometer. The results are shown in FIGS. 43 and 44. From the aboveresults, the effects of the present invention were evidenced.

Example 48

A photovoltaic element (Element No. Example 48) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 44-5 in Example 44, except for a cylinder of NO/Hegas 1079 being used at a flow rate of 0.5 sccm for the i-type layerformed by microwave plasma CVD and 0.05 sccm for the i-type layer formedby RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44, and the results wereequivalent to those of Element No. Example 44-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and O and N atoms wereconfirmed in the i-type layer.

Example 26

A photovoltaic element (Element No. Example 49) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 44-5, except a cylinder of Si₂ H₆ gas was used at aflow rate of 40 sccm, regulated by a mass flow controller 1021 inaccordance with the flow pattern shown in FIG. 25A, during formation ofthe i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44, and the results wereequivalent to those of Element No. Example 44-5.

The distribution in the layer thickness direction of Si and hydrogenatoms in the i-type layer of the photovoltaic element was analyzed usinga secondary ion mass spectrometer (IMS-3F manufactured by CAMECA),resulting in the same tendency as FIG. 25B.

From the above results, it has been found that the effects of theinvention are evidenced in photovoltaic elements in which the content ofhydrogen atoms changes in correspondence with the content of Si atoms.

Example 50

Photovoltaic elements (Elements No. Examples 50-1 to 50-5) werefabricated by forming a reflecting layer, a transparent conductivelayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Element No. Example 44-5, except that the distance betweenthe mixing point of SiH₄ gas and GeH₄ gas and the deposition chamber1001 in the source gas supply unit 1020 was as indicated in Table 37.

For the photovoltaic elements thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 44. Theresults are listed in Table 37. As is seen from Table 37, by making thedistance between the mixing point of SiH₄ gas and GeH₄ gas and thedeposition chamber 1001 equal to or less than 5 m, a photovoltaicelement having further improved characteristics can be obtained.

Example 51

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Example 44-5 of Example 44. A solar cell module wasfabricated using this photovoltaic element and used in an analog clockwith a circuit configuration as shown in FIG. 28.

Comparative Example 13

As a comparative example, a photovoltaic element was fabricated underthe same conditions as those of Element No. Comparative Example 12-6,and using this photovoltaic element, the same analog clock as in Example51 was made.

The analog clocks as fabricated in Example 51 and Comparative Example 13were installed on the wall of a room, and an indoor lamp was lit for 8.5hours a day. As a result, the analog clock of Example 51 worked for theentire day, but the analog clock of Comparative Example 13 did not workthe entire day, whereby the effects of the power generation system ofthe present invention were evidence.

Example 52

A photovoltaic element (Element No. Example 52) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 44-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass flow controllers 1021, 1026 in accordance withthe flow patterns as shown in FIG. 35 during formation of the i-typelayer by microwave plasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 44, andthe results were equivalent to those of Element No. Example 44-5 inExample 44, whereby the effects of the present invention were evidenced.

Example 53

A photovoltaic element (Element No. Example 53) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 44-5, except for using a cylinder of B₂ H₆ (2000 ppm)/H₂ gasinstead of BF₃ (2000 ppm)/H₂ gas at a flow rate of 1 sccm duringformation of the i-type layer by microwave plasma CVD, and 0.5 sccmduring formation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic and the durability characteristicwere measured in the same manner as in the Example 44, and the resultswere equivalent to Element No. Example 44-5, whereby the effects of thepresent invention were evidenced.

Example 54

A photovoltaic element (Element No. Example 54) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on the substrate under the same conditions as thoseof Element No. Example 44-5 in Example 44, except that the flow rate ofNO/He gas was regulated by a mass flow controller 1029 in accordancewith the flow pattern as shown in FIG. 33A, during formation of thei-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 44, and the resultswere equivalent to those of Element No. Example 44-5.

Also, the distribution in the layer thickness direction of N and O atomsin the i-type layer of the photovoltaic element was analyzed using asecondary ion mass spectrometer, resulting in the same tendency asindicated in FIG. 33B. From the above results, the effects of thepresent invention were evidenced.

Example 55

A photovoltaic element (Element No. Example 55) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as thoseof Element No. Example 44-5, except that the flow rates of SiH₄ gas andGeH₄ gas were regulated by mass flow controllers 1021, 1026 inaccordance with the flow patterns as shown in FIG. 34, during formationof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44, and the results wereequivalent to Element No. Example 44-5, whereby the effects of thepresent invention were evidenced.

Example 56

A photovoltaic element (Element No. Example 56) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as Example52, except that the power of the bias power source 1011 was set at 250mW/cm³, and the DC bias was set at 50 V for application to the bias rod1012, during formation of the i-type layer by microwave plasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 52, andthe results were equivalent to those of Example 52, whereby the effectsof the present invention were demonstrated.

Example 57

A photovoltaic element (Element No. Example 57) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as thoseof Element No. Example 44-5 in Example 44, except for using a cylinderof D₂ gas (not shown) instead of H₂ at a flow rate of 300 sccm duringformation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44, and the results wereequivalent to those of Element No. Example 44-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that Datoms were contained in the i-type layer, whereby the effects of thepresent invention were evidenced.

Example 58

A photovoltaic element (Element No. Example 58) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 44, except that the DC bias of bias power source1011 was changed at a constant rate from 50 V to 80 V when the shutter1013 was opened, during formation of the n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 44, and the results wereequivalent to Element Example No. 44-5, whereby the effects of thepresent invention were evidenced.

Example 59

A photovoltaic element (Element No. Example 59-1) was fabricated underthe same fabrication conditions as those of Element No. Example 44-5 inExample 44, except that an n-type layer and a p-type layer were formedunder the same conditions as those of Example 16, using an RF plasma CVDusing deposition apparatus.

A photovoltaic element (Element No. Example 59-2) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofExample 59-1, except that BF₃ (2000 ppm)/H₂ gas and PH₃ (2000 ppm)/H₂gas were not used during formation of the i-type layer by microwaveplasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 44. From the results, it was determined thatthe photovoltaic element of Element No. Example 59-1 was better than thephotovoltaic element of Element No. Example 59-2, i.e., 1.02 timesbetter in the open-circuit voltage and 1.04 times better in the fillfactor of the low illuminance characteristic, and 1.08 times better inthe photovoltaic conversion efficiency of the low illuminancecharacteristic, and 1.07 times better in the decrease in thephotovoltaic conversion efficiency (the durability characteristic),whereby the effects of the present invention were evidenced.

Example 60

A photovoltaic element (Element No. Example 60-1) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as listed in Table 38, with the same method as inExample 44.

A photovoltaic element (Element No. Example 60-2) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as those of Example 60-1, except that the BF₃ (2000ppm)/H₂ gas and PH₃ (2000 ppm)/H₂ gas were not used during formation ofthe first i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 44. From the results, it was evidenced thatthe photovoltaic element of Element No. Example 60-1 was better than thephotovoltaic element of Element No. Example 60-2, i.e., 1.03 timesbetter in the open-circuit voltage and 1.03 times better in the fillfactor of the initial characteristics, 1.08 times better in thephotovoltaic conversion efficiency of the low illuminancecharacteristic, and 1.09 times better in the decrease in thephotovoltaic conversion efficiency (the durability characteristic),whereby the effects of the present invention were demonstrated.

Example 61

A photovoltaic element (Element No. Example 61-1) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as listed in Table 39, with the same method as in Example 44.

A photovoltaic element (Element No. Example 61-2) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Example 61-1, except that the BF₃ (2000 ppm)/H₂ gas andPH₃ (2000 ppm)/H₂ gas were not used during formation of the first andsecond i-type layers by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 44. From the results, it was found that thephotovoltaic element of Element No. Example 61-1 was better than thephotovoltaic element of Element No. Example 61-2, i.e., 1.03 timesbetter in the open-circuit voltage and 1.04 times better in the fillfactor of the initial characteristics, 1.08 times better in thephotovoltaic conversion efficiency of the low illuminancecharacteristic, and 1.07 times better in the decrease in thephotovoltaic conversion efficiency (the durability characteristic),whereby the effects of the present invention were evidenced.

Example 62

A photovoltaic element of the present invention was fabricated using amultiple cheer separation-type deposition apparatus as shown in FIG. 20.The photovoltaic element (Element No. Example 62) was made in accordancewith the procedure of Example 19 under the same layer forming conditionsas Example 60.

For the photovoltaic element this fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 44. Fromthe results, it was determined that the photovoltaic element (ElementNo. Example 62) of Example 62 was better than the photovoltaic element(Element No. Example 60) of Example 60, i.e., 1.01 times better in theopen-circuit voltage and 1.02 times better in the fill factor of theinitial characteristics, 1.03 times better in the photovoltaicconversion efficiency of the low illuminance characteristic, and 1.02times better in the decrease in the photovoltaic conversion efficiency(the durability characteristic), whereby the photovoltaic devices of thepresent invention have better characteristics by fabricating thephotovoltaic element in the multiple chamber separation-type depositionapparatus, whereby the effects of the present invention weredemonstrated.

Example 63

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Example 60-1, whereby a solar cell module was made usingthe photovoltaic element, and a car-mounted ventilation fan using themodule and having a circuit configuration as shown in FIG. 28 wasproduced.

For the comparison, a photovoltaic element was fabricated under the sameconditions as those of Element No. Example 60-2, and a car-mountedventilation fan similar to that of Example 63 was made using thephotovoltaic element.

A car which had mounted therein ventilation fans utilizing Element No.Examples 60-1 to 60-2 was left in an idling state with the enginerunning for 168 hours, and then left in sunny weather with theventilation fan working and with the engine stopped, whereafter thetemperature within the car was measured. As a result, the car-mountedcooling fan of Element No. Example 60-1 achieved an interior temperaturefour degrees lower than the fan of Element No. Example 60-2.

Example 64

In this example, a photovoltaic element wherein a valence electroncontrol agent was doped into the i-type layer formed by microwave plasmaCVD and a laminated p-type layer was fabricated.

The same gas supply unit as in Example 1 was used, except that the BF₃(1%)/H₂ gas cylinder was replaced with a cylinder of B₂ H₆ gas dilutedto 10% with H₂ gas (B₂ H₆ (10%)/H₂ gas) in a source gas supply unit 1020as shown in FIGS. 18 and 19.

On a SUS substrate, a reflecting layer, a reflection multiplying layer,an n-type layer, and an i-type layer formed by microwave plasma CVD wereformed under the same conditions as in Example 44, and then an i-typelayer was formed by RF plasma CVD under the same conditions as those ofthe i-type layer formed by RF plasma CVD in Example 44 except that theBF₃ (2000 ppm)/H₂ gas flow was changed to 0.05 sccm and the PH₃ (2000ppm)/H₂ gas flow to 0.05 sccm. Subsequently, a p-type layer was formedunder the same conditions as the p-type layer in Example 21, wherebyseveral photovoltaic elements were fabricated (Element No. Examples 64-1to 64-7 and Comparative Example 14-1).

The initial characteristics, low illuminance characteristic, anddurability characteristic were measured for the fabricated photovoltaicelements. The results are listed in Table 40. From Table 40, it is seenthat a photovoltaic element having improved characteristics can beobtained by forming the i-type layer by microwave plasma CVD within thedeposition chamber at a pressure of 50 mTorr or less.

Then, photovoltaic elements (Element No. Examples 64-8 to 64-10 andComparative Examples 14-2 to 14-3) were fabricated by forming areflecting layer, a reflection multiplying layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on a substrate under the same conditions as those of ElementNo. Example 64-5, except that the microwave power was as indicated inTable 41, during formation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. The results are listedin Table 41. As seen from Table 41, a photovoltaic element havingexcellent characteristics can be obtained by decomposing the source gaswith a lower microwave energy then the microwave energy necessary todecompose 100% of the source gas.

Then, several photovoltaic elements (Element No. Examples 64-11 to 64-14and Comparative Example 14-4) were fabricated by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as those of Element No. Example64-5, except that the RF bias was as indicated in Table 42 duringformation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 1. The results are in Table 42. As seen inTable 42, a photovoltaic element having excellent characteristics isobtained by applying a higher RF energy to the source gas than themicrowave energy.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 14-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of Element No. Example 64-5, except that the SiH₄gas flow and the GeH₄ gas flow were regulated by mass flow controllers1021, 1026 in accordance with the flow patterns as shown in FIG. 23Bduring formulation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. the results indicatedthat the open-circuit voltage and the fill factor in the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic in Element No. Example 64-5 were, respectively, 1.02times, 1.03 times, 1.07 times, and 1.08 times better than those inElement No. Comparative Example 14-5.

The change in the bandgap of the i-type layer in the layer thicknessdirection was measured, and it was found that the photovoltaic elementof Element No. Example 14-5 had a minimum value of bandgap at a positionshifted toward the interface between the p-type layer and the i-typelayer, away from the central position of the i-type layer.

Next, a photovoltaic element was fabricated (Element No. Example 64-15)by forming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 64-5, except that BF₃ (2000 ppm)/H₂ gas and PH₃(2000 ppm)/H₂ gas were not flowed during fabrication of the i-type layerby microwave plasma CVD.

For the thus fabricated photovoltaic element, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 1. Fromthe results, it was found that the photovoltaic element of Element No.Example 64-5 was superior to that of Element No. Example 64-15, whereinthe open-circuit voltage and the fill factor of the initialcharacteristics, the low illuminance characteristic and the durabilitycharacteristic were, respectively, 1.03 times, 1.02 times, 1.07 times,and 1.07 times better.

Composition analysis of the photovoltaic element of Element No. Example64-5 was performed using a secondary ion mass spectrometer, and it wasconfirmed that B atoms and P atoms were contained in the i-type layerformed by microwave plasma CVD.

Then, several photovoltaic elements (Element No. Examples 64-16 to 64-20and Comparative Example 14-6) were fabricated by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as the photovoltaic element inElement No. Example 64-5, except that the SiH₄ gas flow and the RFdischarge electric power were as indicated in Table 43 during formationof the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 64-5. Theresults are listed in Table 43.

As seen from Table 43, photovoltaic elements having excellentcharacteristics can be fabricated by depositing the i-type layer by RFplasma CVD at a deposition rate of 2 nm/sec or less.

Then, several photovoltaic elements (Element No. Examples 64-21 to 64-23and Comparative Examples 14-7 to 14-8) were fabricated by forming areflecting layer, a reflection multiplying layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on a substrate under the same conditions as Element No.Example 64-5, except that the layer thickness of the i-type layer formedby RF plasma CVD was as indicated in Table 44.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 64-5. Theresults are listed in Table 44. As seen from Table 44, the photovoltaicelements (Element No. Examples 64-21 to 64-23) provided with the i-typelayer formed by RF plasma CVD having a layer thickness of 30 nm or lesshave excellent characteristics.

Then, several photovoltaic elements (Element No. Examples 64-24 to64-27) were fabricated by forming a reflecting layer, a reflectionmultiplying layer, an n-type layer, an i-type layer, a p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as those of the photovoltaic element in Element No.Example 64-5, except that the RF power was as indicated in Table 45during formation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 64-5. Theresults are listed in Table 45. As seen in Table 45, the photovoltaicelements wherein the value of half-width of a peak of 2000 cm⁻¹ in theinfrared absorption spectrum divided by the peak height is greater inthe i-type layer formed by RF plasma CVD than in the i-type layer formedby microwave plasma CVD and had better characteristics.

Next, a photovoltaic element (Element No. Example 64-28) was fabricatedby forming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 64-5, except that doping layer A was not formed in makingthe p-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. From the results, itwas found that the photovoltaic element of Element No. Example 64-5 wassuperior to Element No. Comparative Example 64-28, wherein theopen-circuit voltage and the fill factor of the initial characteristics,the photoelectric conversion efficiency of the low illuminancecharacteristic, and the decrease in the photoelectric conversionefficiency of the durability characteristic, respectively, were 1.04times, 1.02 times, 1.09 times, and 1.07 times better.

From the above results, it has been found that the photovoltaic elementsof the present invention have better characteristics as compared withthe conventional photovoltaic elements. The photovoltaic elements of thepresent invention have been fabricated by a process such that an i-typelayer formed by microwave plasma CVD is deposited at an internalpressure of 50 mTorr or less by simultaneously applying a lowermicrowave energy and a higher RF energy than the microwave energynecessary to decompose 100% of the source gas. An i-type layer formed byRF plasma CVD is deposited 30 nm thick or less on the p-type layer at adeposition rate of 2 nm/sec or less, such that the bandgap smoothlychanges in the direction of layer thickness. The minimum value ofbandgap is at a position shifted toward the interface between the p-typelayer and the i-type layer, away from the central position of the i-typelayer, wherein B and P atoms are doped in the i-type layer formed bymicrowave plasma CVD. The p-type layer and/or the n-type layer has alaminated structure consisting of a layer having a Group III and/orGroup V element as the main constituent and a layer containing a valenceelectron control agent and having silicon atoms as the main constituent.

Example 65

Photovoltaic elements (Element No. Examples 65-1 to 65-8) werefabricated by forming reflecting layer, a reflection multiplying layer,an n-type, an i-type layer, a p-type layer, a transparent electrode, anda collector electrode on a substrate under the same conditions as thoseof Element No. Example 64-5 in Example 64, except that the SiH₄ gas flowand GeH₄ gas flow were regulated by mass flow controllers 1021, 1026 inaccordance with the flow patterns as shown in FIG. 23A, as conducted inExample 64. The SiH₄ gas flow was maintained at 200 sccm and the GeH₄gas flow at 1 sccm, and the region of the maximum bandgap was made tohave a thickness as indicated in Table 46, during form of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64. The results arelisted in Table 46. As seen from Table 46, the photovoltaic elements(Element No. Examples 65-1 to 65-7) having a layer thickness of 1 to 30nm in the region of the maximum bandgap exhibit better characteristics,whereby the effects of the present invention are demonstrated.

Example 66

A photovoltaic element (Element No. Example 66) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 64-5 in Example 64, except for using a cylinder ofAsH₃ /H₂ gas instead of cylinder PH₃ (2000)ppm/H₂ gas at a flow rate of0.2 sccm for the i-type layer formed by microwave plasma CVD, and 0.02sccm for the i-type layer formed by RF plasma CVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 64, and the results wereequivalent to those of Element No. Example 64-5.

Example 67

A photovoltaic element (Element No. Example 67) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 64-5, except that the BF₃ (2000 ppm)/H₂ gas flow andthe PH₃ (2000 ppm)/H₂ gas flow were regulated in accordance with theflow patterns as shown in FIGS. 41 and 42 by the mass flow controllers1027, 1028, during formation of the i-type layer by microwave plasmaCVD. The BF₃ (2000 ppm)/H₂ gas flow and PH₃ (2000 ppm)/H₂ gas flow were3 sccm and 0.04 sccm, during formation of the i-type layer by RF plasmaCVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 64, and the results wereequivalent to those of Element No. 64-5.

Also, the distribution of B and P atoms in the i-type layer was analyzedusing a secondary ion mass spectrometer, resulting in the same tendencyas shown in FIGS. 43 and 44.

Example 68

A photovoltaic element (Element No. Example 68) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 64-5, except for using a cylinder of NO/He gas 1079at a flow rate of 0.5 sccm for the i-type layer formed by microwaveplasma CVD and 0.05 sccm for the i-type layer formed by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to those of Element No. Example 64-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that O andN atoms were contained in the i-type layer. From the above results, theeffects of the present invention could be evidenced.

Example 69

A photovoltaic element (Element No. Example 69) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofElement No. Example 64-5, except for using a cylinder of Si₂ H₆ gas 1079at a flow rate of 40 sccm, regulated by a mass flow controller 1021 inaccordance with the flow pattern as shown in FIG. 18A, during depositionof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristics, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to those of Element No. Example 64-5.

Also, the distribution in the layer thickness direction of Si andhydrogen atoms in the i-type layer of the photovoltaic element wasanalyzed using a secondary ion mass spectrometer, resulting in the sametendency as indicated in FIG. 25B. From the above results, the effectsof the present invention could be evidenced.

Example 70

Photovoltaic elements (Element No. Examples 70-1 to 70-5) werefabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Element No. Example 64-5, except that the distance betweenthe mixing point of SiH₄ gas and GeH₄ gas and the deposition cheer 1001in the source gas supply unit 1020 was set as indicated in Table 47.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64. The results werelisted in Table 47. As seen from Table 47, by making the distancebetween the mixing point of SiH₄ gas and GeH₄ gas and the depositionchamber 1001 equal to or less than 5 m, a photovoltaic element havingfurther improved characteristics can be obtained.

Example 71

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Examples 64-5 and 64-15, a solar cell module wasfabricated using this photovoltaic element, and the module was used as apower source for an analog clock with a circuit configuration as shownin FIG. 28.

The analog clocks as fabricated were installed on the wall of a room. Asa result, the analog clock using Element No. Example 64-5 worked for alonger time than the analog clock using Element No. Example 64-15.

Example 72

A photovoltaic element (Element No. Example 72) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as ElementNo. Example 64-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass flow controllers 1021, 1026 in accordance withthe flow patterns as shown in FIG. 26 during formation of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64, and the results wereequivalent to Element No. Example 64-5, whereby the effects of thepresent invention were demonstrated.

Example 73

A photovoltaic element (Element No. Example 73) was fabricated byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 64-5, except for using a cylinder of B₂ H₆ (2000 ppm)/H₂ gasinstead of BF₃ (2000 ppm)/H₂ gas at a flow rate of 1 sccm duringformation of the i-type layer by microwave plasma CVD and 2 sccm duringformation of the i-type layer formed by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64, and the results wereequivalent to Element No. Example 64-5, whereby the effects of thepresent invention were evidenced.

Example 74

A photovoltaic element (Element No. Example 74) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as ElementNo. Example 64-5, except that the flow rate of NO/He gas was regulatedby a mass flow controller 1029 in accordance with the flow patterns asshown in FIG. 33A, during formation of the i-type layer by microwaveplasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to those of Element No. Example 64-5.

Also, the distribution in the layer thickness direction of N and O atomsin the i-type layer of the photovoltaic element was analyzed using asecondary ion mass spectrometer, resulting in the same tendency asindicated in FIG. 33B. From the above results, the effects of thepresent invention were demonstrated.

Example 75

A photovoltaic element (Element No. Example 75) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as thoseof Element No. Example 64-5, except that the flow rates of SiH₄ gas andGeH₄ gas were regulated by mass flow controllers 1021, 1026 inaccordance with the flow patterns as shown in FIG. 34 during formationof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to Element No. Example 64-5, whereby the effects of thepresent invention were evidenced.

Example 76

Photovoltaic elements (Element No. Examples 76-1 to 76-5) werefabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Element No. Example 64-5, except that the layer thicknessof doping layer A of the p-type layer was as indicated in Table 48.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64. The results arelisted in Table 48. As seen from Table 48, the photovoltaic elements(Element No. Examples 76-1 to 76-4) having a layer thickness of thedoping layer A of 0.01 to 1 nm exhibit better characteristics, wherebythe effects of the present invention are evidenced.

Example 77

A photovoltaic element (Element No. Example 77) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 64-5, except that the doping layer A and the doping layer Bof the n-type layer were formed under the conditions as indicated inTable 25.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to Element No. Example 64-5, whereby the effects of thepresent invention were evidenced.

Example 78

A photovoltaic element (Element No. Example 78) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 64-5, except that the doping layer A and the doping layer Bof the p-type layer were formed under the conditions as indicated inTable 26.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64, and the results wereequivalent to Element No. Example 64-5, whereby the effects of thepresent invention were evidenced.

Example 79

A photovoltaic element (Element No. Example 79) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as Example72, except that the RF bias of the bias power source 1011 was set at 250mW/cm³, and the DC bias was set via a coil at 50 V for application tothe bias rod 1012, during formation of the i-type layer by microwaveplasma CVD.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 72, andthe results were equivalent to those of Example 72, whereby the effectsof the present invention were evidenced.

Example 80

A photovoltaic element (Element No. Example 80) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as ElementNo. Example 64-5, except for using a cylinder of D₂ gas (not shown)instead of H₂ at a flow rate of 300 sccm during formation of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 64, and the resultswere equivalent to those of Element No. Example 64-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that Datoms were contained in the i-type layer, whereby the effects of thepresent invention were evidenced.

Example 81

A photovoltaic element (Element No. Example 81) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate, under the same conditions as thoseof Element No. Example 64-5, except that the DC bias of bias powersource 1011 was changed at a constant rate from 50 V to 80 V when theshutter 1013 was opened, during fabrication of the n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64, and the results wereequivalent to Element No. Example 64-5, whereby the effects of thepresent invention were evidenced.

Example 82

Using a deposition apparatus employing the RF plasma CVD method as shownin FIG. 19, an n-type layer and a p-type layer of laminated structurewere formed by RF plasma CVD. A photovoltaic element (Element No.Example 82-1) was fabricated under the same fabrication conditions asExample 39 for the n-type layer and the p-type layer, and under the samefabrication conditions as Element No. Example 64-5 for the i-type layersformed by microwave plasma CVD and RF plasma CVD.

For comparison, a photovoltaic element (Element No. Example 82-2) wasfabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of Element No. Example 82-1, except that BF₃ (2000ppm)/H₂ gas and PH₃ (2000 ppm)/H₂ gas were not used, during depositionof the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 64. From the results, itwas determined that the photovoltaic element of Element No. Example 82-1was 1.04 times better in the open-circuit voltage and 1.03 times betterin the fill factor of the initial characteristics, 1.08 times better inthe photovoltaic conversion efficiency of the lower illuminancecharacteristic and 1.07 times better in the decrease in the photovoltaicconversion efficiency the durability characteristic) that thephotovoltaic element of Element No. Example 82-2, whereby the effects ofthe present invention were evidenced.

Example 83

A photovoltaic element (Element No. Example 83) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe conditions as indicated in Table 28, except that BF₃ (2000 ppm)/H₂gas was flowed at 0.3 sccm and PH₃ (2000 ppm)/H₂ gas was flowed at 0.5sccm, during fabrication of the first i-type layer by microwave plasmaCVD, with the method of Example 64.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Example 64. Fromthe results, it was determined that the photovoltaic element of ElementNo. Example 83 was 1.03 times better in the open-circuit voltage and1.04 times better in the fill factor of the initial characteristics,1.07 times better in the photovoltaic conversion efficiency of the lowilluminance characteristic, and 1.07 times better in the decrease in thephotovoltaic conversion efficiency (the durability characteristic) thanthe photovoltaic element of Element No. Example 40, whereby the effectsof the present invention were evidenced.

Example 84

A photovoltaic element (Element No. Example 84) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the conditionsas indicated in Table 29, except that BF₃ (2000 ppm)/H₂ gas was flowedat 1 sccm and PH₃ (2000 ppm)/H₂ gas was flowed at 0.3 sccm, duringdeposition of the first i-type layer by microwave plasma CVD, and BF₃(2000 ppm)/H₂ was flowed at 0.5 sccm and PH₃ (2000 ppm)/H₂ gas wasflowed at 0.1 sccm, during deposition of the second i-type layer bymicrowave plasma CVD, with the same method as Example 64.

For the photovoltaic element thus fabricated, the initialcharacteristics, the low illuminance characteristic and the durabilitycharacteristic were measured in the same manner as Example 64. From theresults, it was determined that the photovoltaic element of Element No.Example 84 was 1.03 times better in the open-circuit voltage and 1.03times better in the fill factor of the initial characteristics, 1.08times better in the photovoltaic conversion efficiency of the lowilluminance characteristic, and 1.07 times better in the decrease in thephotovoltaic conversion efficiency (the durability characteristic) thanthe photovoltaic element of Element No. Example 41, whereby the effectsof the present invention were demonstrated.

Example 85

A photovoltaic element (Element No. Example 85) was fabricated by usinga multiple chamber separation-type deposition apparatus as shown in FIG.21. The formation of the photovoltaic element was performed by makingeach layer under the same conditions as in Example 83, in accordancewith Example 42.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 64. From the results, it was determined thatthe photovoltaic element was 1.01 times better in the open-circuitvoltage and 1.02 times better in the fill factor of the initialcharacteristics, 1.02 times better in the photovoltaic conversionefficiency of the low illuminance characteristic, and 1.02 times betterin the decrease in the photovoltaic conversion efficiency (thedurability characteristic) than Element No. Example 83, whereby aphotovoltaic element having better characteristics could be obtained byfabricating the photovoltaic element of the present invention in themultiple chamber separation-type deposition apparatus. Thus, the effectsof the present invention were evidenced.

Example 86

A photovoltaic element was fabricated under the same fabricationconditions as those of Element No. Examples 83 and 40, whereby a solarcell module was formed using the photovoltaic element. A car-mountedventilation fan having a circuit configuration as shown and using thesolar cell module in FIG. 28 was fabricated.

A car with the ventilation fans as fabricated was left in an idlingstate with the engine running for 168 hours, and then left in sunnyweather with the ventilation fan working and with the engine stopped,whereafter the temperature within the car was measured. As a result, thecar-mounted ceiling fan using Element No. Example 83 provided aninterior temperature three degrees lower than the fan using Element No.Example 40, whereby the effects of the power generation system of thepresent invention were evidenced.

Example 87

After the preparation for film formation was completed, as in Example 1,on the substrates 1004, 1104, an n-type layer, RF plasma CVD andmicrowave i-type layers, and a p-type later were formed.

Herein, the film formations up to the n-type layer were performed as inExample 1.

Then, the substrate 1004 was taken out from the deposition chamber 1001,and installed in the deposition cheer 1101 of the RF plasma CDdeposition unit 1100 as shown in FIG. 19, where an i-type layer wasformed by RF plasma CVD.

To make an i-type layer by RF plasma CVD, the substrate 1104 was heatedto 350° C. by the heater 1105, the outflow valves 1041, 1042 and theauxiliary valve 1108 were gradually opened to flow SiH₄ gas and H₂ gasthrough a gas introducing pipe 1103 into the deposition chamber 1101.The inflow rates of the gases were regulated by mass flow controllers1021, 1022 so that the SiH₄ gas flow and H₂ gas flow were 8 sccm and 100sccm. The pressure within the deposition chamber 1101 was set to 0.5Torr by adjusting the conductance valve 1107 while referring to thevacuum gauge 1106.

Thereafter, the output power of an RF power source 1111 was set at 120mW/cm³, and RF electric power was introduced through the RF matching box1112 into the cathode 1102 to excite an RF glow discharge to start thefabrication of an i-type layer by RF plasma CVD on the i-type layer madeby microwave plasma CVD. Upon depositing an i-type layer having a layerthickness of 10 nm, the RF glow discharge was stopped, and the outflowvalves 1041, 1042 and the auxiliary valve 1108 were closed to stop thegas flow into the deposition chamber 1101, whereby the fabrication ofthe i-type layer was completed.

Then, the substrate 1104 was taken out from the deposition chamber 1101,and installed in the deposition chamber 1001 of the microwave plasma CVDdeposition unit 1000 as shown in FIG. 18, where an i-type layer wasformed by microwave plasma CVD.

To form an i-type layer by microwave plasma CVD, the substrate 1004 washeated to 350° C. by the heater 1005, the outflow valves 1041, 1042,1046 and the auxiliary valve 1008 were gradually opened to flow SiH₄gas, H₂ gas, and GeH₄ gas, respectively, through the gas introducingtube 1003 into the deposition chamber 1001.

The inflow rates of the gases were regulated by mass flow controllers1021, 1022, 1026 so that the SiH₄ gas flow, H₂ gas flow, and GeH₄ gasflow were 200 sccm, 500 sccm, and 1 sccm. The pressure within thedeposition chamber 1001 was set to the value as indicated in Table 2 byadjusting the opening of conductance valve 1007 while referring to thevacuum gauge 1006.

Thereafter, the shutter 1013 was closed, the output power of themicrowave power source (not shown) was set at 170 mW/cm³, and microwavepower was introduced through a waveguide (not shown), the waveguideportion 1010, and the dielectric window 1002 into the deposition chamber1001 to excite a microwave glow discharge. Then, the radio frequency(hereinafter abbreviated as "RF") bias of the bias power source 1011 wasset at 350 mW/cm³ and the DC bias was set via a coil at 0 V forapplication to the bias rod 1012. Thereafter, the shutter 1013 wasopened to start fabrication of an i-type layer by microwave plasma CVDon the i-type layer formed by RF plasma CVD, while at the same timeregulating the SiH₄ gas flow and the GeH₄ gas flow in accordance withthe flow patterns as shown in FIG. 14 by means of the mass flowcontrollers 1021, 1026. Upon depositing an i-type layer having a layerthickness of 300 nm, shutter 1013 was closed, the output of themicrowave power supply was stopped, and outflow valves 1041, 1042, 1046and auxiliary valve 1008 were closed to stop the gas inflow intodeposition chamber 1001.

Subsequently, a p-type layer was fabricated under the same conditions asin Example 1.

The fabrication of the p-type layer on the i-type layer by microwaveplasma CVD was started, and upon depositing p-type layer having a layerthickness of 10 nm, the shutter 1013 was closed, the microwave glowdischarge was stopped, and the outflow valves 1041 to 1043 and theauxiliary valve 1008 were closed to stop the gas inflow into thedeposition chamber 1001, whereby the fabrication of the p-type wascompleted.

Further, on the p-type layer, a 70 μm-thick ITO (In₂ O₃ +SnO₂) thin filmas the transparent electrode and a 2 μm-thick aluminum (Al) thin film asthe collector electrode were vapor deposited in vacuum to fabricatephotovoltaic elements (Element No. Examples 87-1 to 87-7, ComparativeExample 87-1). The fabrication conditions of the photovoltaic elementsas above are listed in Table 49.

The initial characteristics, low illuminance characteristic, anddurability characteristic of the fabricated photovoltaic elements werethen measured.

The measurement of the initial characteristics was performed in terms ofthe open-circuit voltage and fill factor obtained by placing thefabricated photovoltaic elements under illumination of AM-1.5 (100mW/cm²) light and measuring the V-I characteristic. The results arelisted in Table 50.

The measurement of the low illuminance characteristic was performed interms of the photoelectric conversion efficiency obtained by installingthe fabricated photovoltaic elements under illumination of AM-1.5 light(10 mW/cm²) and measuring the V-I characteristic. The results ofmeasurement are listed in Table 50.

The measurement of the durability characteristic was performed in termsof the change in the photoelectric conversion efficiency obtained byplacing the fabricated photovoltaic elements in the dark at a humidityof 70% and a temperature of 60° C. and then applying vibrations of 1 mmat 3600 rpm for 48 hours. The results of measurement are listed in Table50.

As seen from Table 50, a photovoltaic element having excellentcharacteristics is fabricated by making the i-type layer by microwaveplasma CVD under a pressure of the deposition chamber 1001 of 50 mTorror less.

Next, using a substrate of barium borosilicate glass (7059 manufacturedby Corning), a microwave plasma CVD i-type layer was formed on thesubstrate by opening the shutter 1013 for two minutes under the sameconditions as the i-type layer formed by microwave plasma CVD in ElementNo. Example 87-5, except that SiH₄ gas flow and GeH₄ gas flow and themicrowave power were as indicated in Table 51, whereby a sample for themeasurement of source gas decomposition efficiency was fabricated(Sample Nos. 87-1 to 87-5).

The film thickness of the fabricated sample for the measurement ofsource gas decomposition efficiency was measured by a layer thicknessmeasuring instrument (alpha step 100 manufactured by TENCOR INSTRUMENTS)to obtain the decomposition efficiency of the source gas. The resultsare listed in Table 51.

Then, photovoltaic elements were fabricated (Element No. Examples 87-8to 87-10 and Comparative Examples 87-2 to 87-3) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 87-5, except that the microwave electric powerwas as indicated in Table 52 during formation of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 87-5. Theresults are listed in Table 52. As seen from Table 52, a photovoltaicelement having excellent characteristics can be obtained by decomposingthe source gas with a lower microwave energy than the microwave energynecessary to decompose 100% of the source gas.

Then, photovoltaic elements were fabricated (Element No. Examples 87-11to 87-14 and Comparative Example 87-4) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on a substrateunder the same conditions as those of the photovoltaic element inElement No. Example 87-5, except that the RF bias was as indicated inTable 53 during formation of the i-type layer by microwave plasma CVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Element No.Example 87-5. The results are listed in Table 53. As seen from Table 53,a photovoltaic element having excellent characteristics can be obtainedby applying a higher RF energy to the source gas than the microwaveenergy.

Next, using a stainless steel substrate and a barium borosilicate glass(7059 manufactured by Corning) substrate, an i-type layer 1 μm thick wasformed on the substrates under the same conditions as the i-type layerformed by microwave plasma CVD in Element No. Example 87-5, except thatthe SiH₄ gas flow and GeH₄ gas flow were as indicated in Table 54,whereby a sample for the measurement of the material properties wasfabricated (Sample Nos. 87-6 to 87-10).

Further, using a barium borosilicate glass (7059 manufactured byCorning) substrate, an i-type layer 1 μm thick was formed on thesubstrate under the same conditions as the i-type layer formed by RFplasma CVD in Element No. Example 87-5, whereby another sample for themeasurement of material properties was fabricated (Sample No. 87-11).

The bandgap and the composition of the fabricated samples for themeasurement of material properties were determined to obtained therelation between the composition ratio of Si to Ge atoms and thebandgap.

The measurement of bandgap was performed as in Example 1 to obtain thebandgap of the i-type layer.

Also, the composition analysis was performed in the same manner as inExample 1 to measure the composition ratio of Si atoms to Ge atoms. Theresults of bandgap and composition analysis are shown in Table 54.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 87-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on the substrate under the sameconditions as those of the photovoltaic element in Element No. Example87-5, except that the SiH₄ gas flow and GeH₄ gas flow were regulated bythe mass flow controllers 1021, 1026 in accordance with the flowpatterns as shown in FIG. 14 during formation of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Element No. Example 87-5. The results indicated thatthe open-circuit voltage and the fill factor of the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic in Element No. Example 87-5 were, respectively, 1.02times, 1.03 times, 1.08 times, and 1.07 times better than Element No.Comparative Example 87-5.

Next, the composition analysis in the layer thickness direction of Siand Ge atoms in the i-type layer formed by microwave plasma CVD inElement No. Example 87-5 and Comparative Example 87-5 was performed inthe same manner as the previous composition analysis. From the relationbetween the composition ratio of Si atoms to Ge atoms and the bandgapobtained by Sample Nos. 87-6 to 87-10 as previously described, thevariation of the bandgap in the layer thickness direction of the i-typelayer formed by microwave plasma CVD was obtained. The results are shownin FIG. 24. As seen from FIG. 24, the photovoltaic element in ElementNo. Example 87-5 has a minimum value of bandgap at a position shiftedtoward the interface between the p-type layer and the i-type layer, awayfrom the central position of the i-type layer, while the photovoltaicelement in Element No. Comparative Example 87-5 has a minimum value ofbandgap at a position shifted toward the interface between the n-typelayer and the i-type layer, away from the central position of the i-typelayer.

Then, photovoltaic elements were fabricated (Element No. Examples 87-15to 87-19 and Comparative Example 87-6) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode, and a collector electrode on a substrateunder the same conditions as those of the photovoltaic element inElement No. Example 87-5, except that SiH₄ gas flow and RF dischargepower were as indicated in Table 55 during fabrication of the i-typelayer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 87-5. Theresults are listed in Table 55.

Next, using a barium borosilicate glass (7059 manufactured by Corning)substrate, an i-type layer 1 μm thick was formed on the substrate underthe same conditions as the i-type layer formed by RF plasma CVD inElement No. Example 87-5, except that the SiH₄ gas flow and the RFdischarge power were as indicated in Table 55, whereby samples for themeasurement of deposition rate were fabricated (Sample Nos. 87-12 to87-17). The deposition rate of the fabricated samples was obtained inthe same manner as in Sample Nos. 87-1 to 87-5. The results are listedin Table 55.

As seen from Table 55, a photovoltaic element having excellentcharacteristics is obtained by making the i-type layer by RF plasma CVDat a deposition rate of 2 nm/sec or less.

Then, photovoltaic elements were fabricated (Element No. Examples 87-20to 87-22 and Comparative Examples 87-7 to 87-8) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode on asubstrate under the same conditions as in Element No. Example 87-5,except that the layer thickness of the RF plasma CVD i-type layer was asindicated in Table 56.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 87-5. Theresults are listed in Table 56. As seen from Table 56, the photovoltaicelement provided with a i-type layer formed by RF plasma CVD having alayer thickness of 30 nm or less (Element No. Examples 87-20 to 87-22)has excellent characteristics.

Next, using a single crystal silicon substrate, a 1 μm thick i-typelayer formed by RF plasma CVD was deposited on the substrate under thesame conditions as the i-type layer formed by RF plasma CVD in ElementNo. Example 87-5, except that the RF discharge power was as indicated inTable 57, whereby samples for the measurement of infrared spectrum werefabricated (Sample Nos. 87-18 to 87-22).

Further, using a single crystal silicon substrate, a 1 μm thick i-typelayer formed by microwave plasma CVD was deposited 1 μm thick on thesubstrate under the same conditions as the i-type layer formed bymicrowave plasma CVD in Element No. Example 87-5, whereby a sample forthe measurement of the infrared spectrum was fabricated (Sample No.87-23).

The sample for the measurement of infrared spectrum (Sample Nos. 87-18to 87-23) was placed in an infrared spectrophotometer (1720-Xmanufactured by PERKIN ELMER) to obtain the value of the half-width at apeak of 2000 cm⁻¹ in the infrared absorption spectrum divided by theheight of the peak. The results are in Table 57.

Then, photovoltaic elements were fabricated (Element No. Examples 87-23to 87-26) by forming a reflecting layer, a reflection multiplying layer,an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example87-5, except that the RF discharge power was as indicated in Table 57during fabrication of the i-type layer by RF plasma CVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured int he same manner as in Element No.Example 87-5. The results are listed in Table 57. As seen from Table 57,the photovoltaic elements having a greater value of half-width at a peakof 2000 cm¹ in the infrared absorption spectrum divided by the height ofthe peak in the i-type layer formed by RF plasma CVD rather than in thei-type layer formed by microwave plasma CVD have better characteristics.

From the above results, it has been found that the photovoltaic elements(Element No. Examples 87-1 to 87-23) of the present invention havebetter characteristics than the conventional photovoltaic elements(Element No. Comparative Examples 87-1 to 87-8). The photovoltaicelements of the present invention have been fabricated by a processwherein an i-type layer formed by microwave plasma CVD is deposited atan internal pressure of 50 mTorr or less by applying to the source gas alower microwave energy and higher RF energy then the microwave energynecessary to decompose 100% of the source gas. An i-type layer formed byRF plasma CVD is deposited 30 nm thick or less at a deposition rate of 2nm/sec or less, in such a manner that the bandgap smoothly changes inthe direction of layer thickness, and the minimum value of bandgap is ata position shifted toward the interface between the p-type layer and thei-type layer, away from the central position of the i-type layer. Thus,the effects of the present invention have been demonstrated.

Example 88

Photovoltaic elements were fabricated (Element No. Examples 88-1 to88-8) by forming a reflecting layer, a transparent conductive layer, ann-type layer, an i-type layer, a p-type layer, a transparent electrode,and a collector electrode on a substrate under the same conditions asthose of Element No. Example 87-5, except that after the SiH₄ gas flowand GeH₄ gas flow were regulated by the mass flow patterns as shown inFIG. 14, as in Example 1, the SiH₄ gas flow was maintained at 200 sccmand the GeH₂ gas flow at 1 sccm. The region of the maximum value ofbandgap was made to have a layer thickness as indicated in Table 58during formation of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. The results are listedin Table 58. As seen from Table 58, the photovoltaic elements (ElementNo. Examples 88-1 to 88-7) having a layer thickness of 1 to 30 nm in theregion of the maximum value of the bandgap have excellentcharacteristics, whereby the effects of the present invention have beenevidenced.

Example 89

A photovoltaic element was fabricated (Element No. Example 89) byforming a reflecting layer, a transparent conductive layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except that BF₃ (2000 ppm)/H₂ gas and PH₃ (2000ppm)/H₂ gas were flowed at 0.04 sccm and 0.02 sccm, using cylinder 1077and cylinder 1078, respectively, during fabrication of the i-type layerby RF plasma CVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 87-5.

Also, composition analysis of Element No. Example 89 was performed usinga secondary ion mass spectrometer (IMS-3F manufactured by CAMECA), andit was confirmed that B and P atoms were contained in the i-type layerformed by RF plasma CVD.

Example 90

A photovoltaic element was fabricated (Element No. Example 90) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, and i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofExample 89, except for using a cylinder of AsH₃ gas diluted to 2000 ppmwith H₂ gas (hereinafter abbreviated as "AsH₃ /H₂ "), instead of PH₃(2000 ppm)/H₂ gas at a flow rate of 0.1 sccm during fabrication of thei-type layer by RF plasma CVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1, and the results wereequivalent to those of Element No. Example 89.

Example 91

A photovoltaic element was fabricated (Element No. Example 91) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except for using a cylinder of NO/He gas 1079 at aflow rate of 0.5 sccm for the i-type layer formed by microwave plasmaCVD and 0.05 sccm for the i-type layer formed by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic and the durability characteristicwere measured in the same manner as in the Example 1, and the resultswere equivalent to those of Element No. Example 87-5.

Also, composition analysis of Element No. Example 91 was performed usinga secondary ion mass spectrometer, and it was confirmed that N and Oatoms were contained in the i-type layer.

Example 92

A photovoltaic element was fabricated (Element No. Example 92) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except for using a cylinder of Si₂ H₆ gas at a flowrate of 40 sccm, regulating the flow rate of SiH₄ gas by a mass flowcontroller 1021 in accordance with the flow pattern as shown in FIG.25A, during fabrication of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 1, and the resultswere equivalent to those of Element No. Example 87-5.

Also, the distribution in the layer thickness direction of Si andhydrogen atoms in the i-type layer of the photovoltaic element wasanalyzed using a secondary ion mass spectrometer (IMS-3F manufactured byCAMECA). The results are shown in FIG. 25B.

From the above results, it has been found that the photovoltaic elementin which the content of hydrogen atoms change corresponding to thecontent of Si atoms has excellent characteristics, whereby the effectsof the present invention have been evidenced.

Example 93

Photovoltaic elements were fabricated (Element No. Examples 93-1 to93-5) by forming a reflecting layer, a reflection multiplying layer, ann-type layer, an i-type layer, a p-type layer, a transparent electrode,and a collector electrode on a substrate under the same conditions asElement No. Example 87-5, except that the distance between the point ofmixing SiH₄ gas and GeH₄ gas and the deposition cheer 1001 in the sourcegas supply unit 1020 was set as listed in Table 59.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1. The results are listedin Table 59. As seen from Table 59, if the distance between the point ofmixing SiH₄ gas and GeH₄ gas and the deposition chamber 1001 is 5 m orless, a photovoltaic element having further improved characteristics canbe obtained.

Example 94

A photovoltaic element was fabricated under the same conditions as inElement No. Example 87-5, and using this photovoltaic element, a solarcell module was fabricated, wherefrom an analog clock with a circuitconfiguration as shown in FIG. 28 was made. In FIG. 28, the electricpower generated by a solar cell module 9101 is passed via a reversecurrent preventing diode 9102 to charge a secondary cell 9104. 9103 isan overcharge preventing diode.

The electric power from the solar cell module 9101 and the secondarycell 9104 is supplied to a drive circuit 9105 of the analog clock.

Comparative Example 88

As a comparative example, a photovoltaic element was fabricated underthe same conditions as in Element No. 88-7, and using this photovoltaicelement, the same analog clock as in Example 8 was made.

The analog clocks as fabricated in Example 94 and Comparative Example 88were installed on a wall within a room, and an indoor lamp was lit for8.5 hours a day. As a result, the analog clock of Example 94 worked theentire day, but the analog clock of the comparative example did not workthe entire day, whereby the effects of the power generation system ofthe present invention were demonstrated.

Example 95

A photovoltaic element was fabricated (Element No. Example 95) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass flow controllers 1021, 1026 in accordance withthe flow patterns as shown in FIG. 26 during fabrication of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to Element No. Example 87-5, whereby the effects of thepresent invention were evidenced.

Example 96

A photovoltaic element was fabricated (Element No. Example 96) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except for using a cylinder of B₂ H₆ gas diluted to 1%with H₂ gas (hereinafter abbreviated as "B₂ H₆ (1%)/H₂ ") instead of BF₃(2000 ppm)/H₂ gas, at a flow rate of 0.05 sccm during deposition of thei-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 1, and the resultswere equivalent to Element No. Example 87-5, whereby the effects of thepresent invention were evidenced.

Example 97

A photovoltaic element was fabricated (Element No. Example 97) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except that the flow rate of NO/He gas was regulatedby a mass flow controller 1029 in accordance with the flow pattern asshown in FIGS. 33A and 33B during formation of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristics, and the durability characteristicwere measured in the same manner as in the Example 1, and the resultswere equivalent to Element No. Example 87-5.

The distribution in the layer thickness direction of N and O atoms inthe i-type layer of the photovoltaic element was analyzed using asecondary ion mass spectrometer. The results are in FIGS. 33A and 33B.From the above results, the effects of the present invention weredemonstrated.

Example 98

A photovoltaic element was fabricated (Element No. Example 98) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass flow controllers 1021, 1026 in accordance withthe flow patterns as shown in FIG. 37 during formation of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to Element No. Example 87-5, whereby the effects of thepresent invention were evidenced.

Example 99

A photovoltaic element was fabricated (Element No. Example 99) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofExample 95, except that the RF bias of the bias power source 1011 wasset at 250 mW/cm³, and the DC bias was set via a coil at 50 V forapplication to the bias rod 1012 during deposition of the i-type layerby microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 95, and the results wereequivalent to those of the Example 95, whereby the effects of thepresent invention were evidenced.

Example 100

A photovoltaic element was fabricated (Element No. Example 100) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except for using a cylinder of D₂ gas (not shown)instead of H₂ at flow rate of 300 sccm during formation of the i-typelayer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 1, and the resultswere equivalent to those of Element No. Example 87-5.

Also, the composition of the photovoltaic element was performed using asecondary ion mass spectrometer, and it was confirmed that D atoms werecontained in the i-type layer, whereby the effects of the presentinvention were demonstrated.

Example 101

A photovoltaic element was fabricated (Element No. Example 101) byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 87-5, except that the DC bias of the bias power source 1011was changed at a constant rate from 50 V to 80 V when the shutter 1013was opened during deposition of the n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 1, and the results wereequivalent to Element No. Example 87-5, whereby the effects of thepresent invention were evidenced.

Example 102

Using an RF plasma CVD manufacturing apparatus as shown in FIG. 19, ann-type layer and a p-type layer of a photovoltaic element of the presentinvention were fabricated by the same procedure as that for the i-typelayer formed by RF plasma CVD of Example 87.

To make the n-type layer, the substrate 1104 was heated to 350° C. bythe heater 1105, the outflow valves 1042, 1044, 1045 and the auxiliaryvalve 1108 were gradually opened to flow H₂ gas, PH₃ (1%)/H₂ gas and Si₂H₆ gas through the gas introducing pipe 1103 into the deposition chamber1101. The inflow rates of the gases were regulated by mass flowcontrollers 1022, 1024, 1025 so that the H₂ gas flow, the PH₃ (1%)/H₂gas flow, and the Si₂ H₆ gas flow were 50 sccm, 5 sccm, and 3 sccm. Thepressure within the deposition chamber 1101 was set at 1 Torr byadjusting the conductance valve 1107 while referring to the vacuum gauge1106.

Thereafter, the output power of RF power source 1111 was set at 120mW/cm², and RF electric power was introduced through the RF matching box1112 into the cathode 1102 to excite an RF glow discharge to start theformation of the n-type layer on the substrate 1104. Upon forming ann-type layer having a thickness of 10 nm, the RF glow discharge wasstopped, and the outflow valves 1042, 1044, 1045 and the auxiliary valve1108 were closed to stop the gas inflow into the deposition cheer 1101,whereby the formation of the n-type layer was completed.

Then, an RF plasma CVD i-type layer was formed on the n-type layer underthe same conditions as those of Element No. Example 87-5.

Then, the substrate 1104 having the i-type layer formed by RF plasma CVDthereon was taken out from the deposition chamber 1101, and placed inthe microwave plasma CVD deposition apparatus 1000 as used in Example87, where an i-type layer was deposited on the i-type layer formed by RFplasma CVD under the same conditions as those of Element No. Example87-5.

Substrate 1004 having the i-type layer formed by microwave plasma CVDthereon was taken out from the deposition chamber 1000, and installed inthe RF plasma CVD deposition apparatus 1100, as previously described,where a p-type layer was made on the i-type layer by RF plasma CVD.

To make the p-type layer, the substrate 1104 was heated to 200° C. bythe heater 1105, the outflow valves 1041 to 1043 and the auxiliary valve1108 were gradually opened to flow SiH₄ gas, H₂ gas, and BF₃ (1%)/H₂ gasthrough the gas introducing tube 1103 into the deposition chamber 1101.The inflow rates of those gases were regulated by mass flow controllers1021 to 1023 so that the SiH₄ gas flow, H₂ gas flow, and BF₃ (1%)/H₂ gasflow were 0.5 sccm, 100 sccm and 1 sccm. The opening of conductancevalve 1107 was adjusted by referring to the vacuum gauge 1106 so thatthe pressure within the deposition cheer 1101 was 1 Torr.

Thereafter, the output power of RF power source 1211 was set at 2mW/cm², and RF electric power was introduced through the RF matching box1112 into the cathode 1102 to excite an RF glow discharge to start theformation of the p-type layer on the i-type layer. Upon forming thep-type layer 5 nm thick, the RF glow discharge was stopped, and outflowvalves 1041 to 1043 and the auxiliary valve 1108 were closed to stop thegas inflow into the deposition chamber 1001, whereby the formation ofthe p-type layer was completed.

Next, on the p-type layer, a transparent electrode and a collectorelectrode were vapor deposited to fabricate a photovoltaic element(Element No. Example 102). The fabrication conditions for thephotovoltaic element as described above are listed in Table 61.

Comparative Example 89

A photovoltaic element was fabricated (Element No. Comparative Example89) by forming a reflecting layer, a reflection multiplying layer, ann-type layer, an i-type layer, a p-type layer, a transparent electrode,and a collector electrode on a substrate under the same conditions asthose of Element No. Example 102, except that the RF plasma CVD i-typelayer was not formed.

For the fabricated photovoltaic elements (Element No. Example 102 andComparative Example 89), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured in the same manner as in Example 1. From the measurements, itwas demonstrated that the photovoltaic element of Element No. Example102 was superior to Comparative Example 89, such that the open-circuitvoltage and the fill factor of the initial characteristics, thephotoelectric conversion efficiency of the low illuminancecharacteristic, and the decrease in the photoelectric conversionefficiency (the durability characteristic) were 1.04 times, 1.03 times,1.8 times, and 1.09 times better, respectively. Thus, the effects of thepresent invention were evidenced.

Example 103

A photovoltaic element was fabricated (Element No. Example 103) byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on the substrate underthe conditions of Table 62, with the same method as in Example 1.

Comparative Example 90

A photovoltaic element was fabricated (Element No. Comparative Example90) by forming a reflecting layer, a reflection multiplying layer, afirst n-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on the substrate underthe conditions as those of Example 103, except that the first i-typelayer 1 and RF plasma CVD i-type layer 2 were not made.

For the fabricated photovoltaic elements (Element No. Example 103 andComparative Example 90) the initial characteristics, the low illuminancecharacteristic, and the durability characteristic were measured as inExample 1. From the measurements, it was demonstrated that thephotovoltaic element of Element No. Example 103 was superior to that ofComparative Example 90, such that the open-circuit voltage and the fillfactor of the initial characteristics, the photoelectric conversionefficiency of the low illuminance characteristic, and the decrease inthe photoelectric conversion efficiency (the durability characteristic)were 1.03 times, 1.03 times, 1.08 times and 1.10 times better,respectively. Thus, the effects of the present invention were evidenced.

Example 104

A photovoltaic element was fabricated (Element No. Example 104) byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the conditionsof Table 63, with the same method as in Example 1.

Comparative Example 91

A photovoltaic element was fabricated (Element No. Comparative Example91) by forming a reflecting layer, a reflection multiplying layer, afirst n-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as above, except that the first i-type layer and the secondi-type layer 1 and RF plasma CVD i-type layer 2 were not made.

For the fabricated photovoltaic elements (Element No. Example 104 andComparative Example 91), the initial characteristics, the lowilluminance characteristic, and the durability characteristic weremeasured as in Example 1. From the measurements, it was shown that thephotovoltaic element of Element No. Example 104 was superior toComparative Example 91, such that the open-circuit voltage and fillfactor of the initial characteristics, the photoelectric conversionefficiency of the low illuminance characteristics, and the decrease inthe photoelectric conversion efficiency (the durability characteristic)were 1.03 times, 1.03 times, 1.09 times and 1.07 times better,respectively. Thus, the effects of the present invention were shown.

Example 105

Using the multiple chamber separation-type deposition apparatus of FIG.22, a photovoltaic element of the present invention was fabricated. Inthe figure, 21201 and 21210 are a load chamber and an unload chamber,respectively, 21202, 21203, 21205 to 21207, and 21209 are chambers forthe deposition of layers by RF plasma CVD as in Example 102, 21204 and21208 are chambers for the deposition of layers by microwave plasma CVDas in Example 87, 21211 to 21219 are gate valves for separating onechamber form the other, 21221, 21222, 21224 to 21226 and 21228 arecathode electrodes, and 21223 and 21227 are, respectively, a waveguideportion for microwaves and a dielectric window.

First, the substrate was installed in the load chamber 21201, and theload chamber 21201 was evacuated of air. Thereafter, gate valve 21211was opened, the substrate was moved to a first n-type layer depositionchamber 21202, and gate valve 21211 was closed. Next, the first n-typelayer was formed on the substrate under the same conditions as those ofthe first n-type layer of Example 103. Then, gate valve 21212 wasopened, the substrate was moved to a first RF plasma CVD i-type layerdeposition chamber 21203, and gate valve 21212 was closed. Next, a firstRF plasma CVD i-type layer 1 was formed on the first n-type layer underthe same conditions as those of the first RF plasma CVD i-type layer 1of Example 103. Next, gate valve 21213 was opened, the substrate wasmoved to a first microwave plasma CVD i-type layer deposition chamber21204, and gate valve 21213 was closed. Next, a first microwave plasmaCVD i-type layer was formed on the first i-type layer 1 formed by RFplasma CVD under the same conditions as those of the first i-type layerformed by microwave plasma CVD of Example 103. Then, gate valve 21214was opened, the substrate was moved to a first RF plasma CVD i-typelayer deposition chamber 21205, and gate valve 21214 was closed. Next, afirst RF plasma CVD i-type layer 2 was formed on the first i-type layerby microwave plasma CVD under the same conditions as those of the firsti-type layer 2 formed by RF plasma CVD of Example 103.

Then, gate valve 21215 was opened, the substrate was moved to a firstp-type layer deposition chamber 21206, and gate valve 21215 was closed.Next, a first p-type layer was formed on the first i-type layer 2 by RFplasma CVD under the same conditions as those of the first p-type layerof Example 103. Then, gate valve 21216 was opened, the substrate wasmoved to a second n-type layer deposition cheer 21207, and gate valve21216 was closed. Next, a second n-type layer was formed on the firstp-type layer under the same conditions as those of the second n-typelayer of Example 103. Next, gate valve 21217 was opened, the substratewas moved to a second i-type layer deposition cheer 21208, and gatevalve 21217 was closed. Next, a second i-type layer was formed on thesecond n-type layer under the same conditions as those of the secondi-type layer of Example 103. Then, gate valve 21218 was opened, thesubstrate was moved to a second p-type layer deposition chamber 21209,and gate valve 21218 was closed. Next, a second p-type layer was formedon the second i-type layer under the same conditions as those of thesecond p-type layer of Example 103. Then, gate valve 21219 was opened,the substrate was moved to an unload chamber 21210, and gate valve 21219was closed. Then, the substrate was taken out from unload chamber 21210,whereby the photovoltaic element fabrication was completed (Element No.Example 105).

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 1. From the measurements, it was found thatthe photovoltaic element was superior to that of Element No. Example103, such that the open-circuit voltage and the fill factor of theinitial characteristics, the photoelectric conversion efficiency of thelow illuminance characteristic, and the decrease in the photoelectricconversion efficiency (the durability characteristic) were 1.01 times,1.02 times, 1.03 times and 1.02 times better, respectively. Therefore,it has been shown that a photovoltaic element of the present inventionexhibits better characteristics by fabricating it in a multiple chamberseparation-type deposition chamber. Thus, the effects of the presentinvention were evidenced.

Example 106

A photovoltaic element was fabricated under the same conditions as thoseof Example 103, and using the photovoltaic element, a solar cell modulewas fabricated to make a car-mounted ventilation fan having a circuitconfiguration as shown in FIG. 28. In FIG. 28, the electric powergenerated by the solar cell module 9101 which is bonded to the bonnet ofthe car is charged through a reverse-current preventing diode 9102 intoa secondary cell 9104. 9103 is an overcharge preventing diode. Theelectric power from the solar cell module 9101 and the secondary cell9104 is supplied to a motor 9105 for a ventilation fan.

Comparative Example 92

As a comparative example, a photovoltaic element was fabricated underthe same conditions as those of Comparative Example 90, and acar-mounted ventilation fan similar to that of the Example 106 was madeusing the photovoltaic element.

A car mounted with the car-mounted ventilation fans as fabricated inExample 106 and Comparative Example 92 was left in an idling state withthe engine running for 168 hours, and then left in sunny weather withthe ventilation fan working and with the engine stopped, whereafter thetemperature within the car was measured. As a result, the car-mountedcooling fan of Example 106 achieved an interior temperature threedegrees lower than the fan of Comparative Example 92, whereby theeffects of the power generation system of the present invention wereevidenced.

Example 107

Using a microwave plasma CVD manufacturing apparatus comprising a sourcegas supply unit 1020 and a deposition unit 1000 as shown in FIG. 18 andan RF plasma CVD manufacturing apparatus with the RF plasma CVD methodcomprising a source gas supply unit 1020 and a deposition unit 1100 asshown in FIG. 19, a photovoltaic element of the present invention wasfabricated. In this example, B and P atoms were doped into the i-typelayer formed by microwave plasma CVD.

On a substrate, a reflecting layer, a reflection multiplying layer, anda n-type layer were formed under the same conditions as those of ElementNo. Example 87-5 of Example 87, and subsequently, the formation ofi-type layers by RF plasma CVD and microwave plasma CVD was performed inthe following manner.

The substrate 1004 was placed in the deposition chamber 1101 of the RFplasma CVD deposition unit 1100 of FIG. 19, where an RF plasma CVDi-type layer was formed.

To form the i-type layer by RF plasma CVD, the substrate 1104 was heatedto 350° C. by the heater 1105, the outflow valves 1041, 1042, 1047, 1048and the auxiliary valves 1008 were gradually opened to flow SiH₄ gas, H₂gas, BF₃ (2000 ppm)/H₂ gas, and PH₃ (2000 ppm)/H₂ through the gasintroducing tube 1103 into the deposition chamber 1101. The inflow ratesof the gases were regulated by mass flow controllers 1021, 1022, 1027,1028 so that the SiH₄ gas, H₂ gas, BF₃ (2000 ppm)/H₂ gas, and PH₃ (2000ppm)/H₂ gas flow were 8 sccm, 100 sccm, 0.04 sccm and 1 sccm. Thepressure within the deposition chamber 1101 was set to 0.5 Torr byadjusting the opening of conductance valve 1107 while referring to thevacuum gauge 1106.

Thereafter, the output power of RF power source 1111 was set at 120mW/cm³, and RF electric power was introduced through RF matching box1112 to cathode 1102 to excite an RF glow discharge to start fabricationof an i-type layer by RF plasma CVD on the n-type layer. Upon making thei-type layer 10 nm thick, the RF glow discharge was stopped, and outflowvalves 1041, 1042, and auxiliary valve 1108 were closed to stop the gasinflow into deposition chamber 1101, whereby the formation of the i-typelayer was completed.

Then, the substrate 1104 was taken out from the deposition chamber 1101,and placed in the deposition chamber 1001 of the microwave plasma CVDdeposition unit 1000 as shown in FIG. 18, where microwave plasma CVDi-type layer was formed.

To form the i-type layer by microwave plasma CVD, the substrate 1004 washeated to 350° C. by the heater 1005, the outflow valves 1041, 1042,1046 to 1048 and the auxiliary valve 1008 were gradually opened to flowSiH₄ gas, H₂ gas, GeH₄ gas, BF₃ (2000 ppm)/H₂ gas, and PH₃ (2000 ppm)/H₂gas through the gas introducing pipe 1003 into the deposition chamber1001. The inflow rates of the gases were regulated by mass flowcontrollers 1021, 1022, 1026 to 1028 so that the SiH₄ gas flow, H₂ gasflow, GeH₄ gas flow, BF₃ (2000 ppm)/H₂ gas flow, and PH₃ (2000 ppm)/H₂gas flow were 200 sccm, 500 sccm, 1 sccm, 0.2 sccm and 0.1 sccm. Thepressure within the deposition chamber 1001 was set to the values inTable 16 by adjusting the opening of conductance valve 1007 whilereferring to the vacuum gauge 1006.

Then, shutter 1013 was closed, the output power of a microwave powersource (not shown) was set at 170 mW/cm³, and microwave power wasintroduced through a waveguide (not shown), the waveguide portion 1010,and the dielectric window 1002 into the deposition chamber 1001 toexcite a microwave glow discharge. Then, the RF bias of bias powersource 1011 was set at 350 mW/cm³, and the DC bias was set via a coil at0 V, and applied to the bias rod 1012. Thereafter, the shutter 1013 wasopened to start fabrication of an i-type layer by microwave plasma CVDon the i-type layer formed by RF plasma CVD, while at the same timeregulating the SiH₄ gas flow and the GeH₂ gas flow in accordance withthe flow patterns as indicated in FIG. 14, by means of the mass flowcontrollers 1021, 1026. Upon forming an i-type layer having a layerthickness of 300 nm, the shutter 1013 was closed, the output of biaspower source 1011 was turned off, the microwave glow discharge wasstopped, and the outflow valves 1041, 1042, 1046 and the auxiliary valve1008 were closed to stop the gas flow into the deposition chamber 1001.

Subsequently, a p-type layer was formed on the i-type layer by RF plasmaCVD under the same conditions as those of Example 1. Further, on thep-type layer, a 70 μm-thick ITO (In₂ O₃ +SnO₂) thin film as thetransparent electrode and a 2 μm-thick aluminum (Al) thin film as thecollector electrode were vapor deposited in vacuum to fabricatephotovoltaic elements (Element No. Examples 107-1 to 107-7 andComparative Example 93-1).

The initial characteristics, low illuminance characteristics anddurability characteristic were measured for the fabricated photovoltaicelements. The results are listed in Table 64. As seen from Table 64, aphotovoltaic element having excellent characteristics can be fabricatedby forming the i-type layer by microwave plasma CVD with the pressure ofthe deposition chamber 1001 being 50 mTorr or less.

Next, using a substrate made of barium borosilicate glass (7059manufactured by Corning), an i-type layer formed by microwave plasma CVDwas deposited on the substrate by opening the shutter 1013 for twominutes under the same fabrication conditions as the i-type layer formedby microwave plasma CVD in Element No. Example 107-5, except that SiH₄gas flow and the microwave power were as indicated in Table 51, wherebythe decomposition efficiency of the source gas was obtained inaccordance with the layer thickness, and the same results of Table 51were obtained.

Then, photovoltaic elements (Element No. Examples 107-8 to 107-10 andComparative Examples 93-2 to 93-3) were fabricated by forming areflecting layer, a reflection multiplying layer, an n-type layer, ani-type layer, a p-type layer, a transparent electrode, and a collectorelectrode on a substrate under the same conditions as those of thephotovoltaic element in Element No. Example 107-5, except that themicrowave power was as indicated in Table 65, during fabrication ofi-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 107-5. Theresults are listed in Table 65. As seen from Table 65, a photovoltaicelement having excellent characteristics can be obtained by decomposingthe source gas with a lower microwave energy then the microwave energynecessary to decompose 100% of the source gas.

Then, photovoltaic elements (Element No. Examples 107-11 to 107-14 andComparative Example 93-4) were fabricated by forming a reflecting layer,a reflection multiplying layer, an n-type layer, an i-type layer, ap-type layer, a transparent electrode, and a collector electrode asubstrate under the same conditions as those of the photovoltaic elementin Element No. Example 107-5, except that the RF bias was as indicatedin Table 66 during formation of the i-type layer by microwave plasmaCVD.

For the thus fabricated photovoltaic elements, the initialcharacteristics, the low illuminance characteristic and the durabilitycharacteristic were measured in the same manner as in Element No.Example 107-5. The results are listed in Table 66. As seen from Table66, a photovoltaic element having excellent characteristics can beobtained by applying a higher RF energy to the source gas than themicrowave energy.

Next, using a stainless steel substrate, a 1 μm thick i-type layer wasformed on the substrate under the same conditions as the i-type layerformed by microwave plasma CVD in Element No. Example 107-5, except thatthe SiH₄ gas flow and GeH₄ gas flow were as shown in Table 57, whereby asample for the measurement of material was fabricated. Further, using abarium borosilicate glass (7059 manufactured by Corning) substrate, a 1μm thick i-type layer was formed on the substrate under the sameconditions as the i-type layer by RF plasma CVD in Element No. Example107-5, whereby a sample for the measurement of material was fabricated.

The bandgap and the composition analysis of the fabricated samples forthe measurement of material properties were conducted to obtain therelation between the composition ratio of Si to Ge atoms and thebandgap, with the same results as in Table 57.

Then, a photovoltaic element was fabricated (Element No. ComparativeExample 93-5) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example107-5, except that the SiH₄ gas flow and GeH₂ gas flow were regulated bythe mass flow controllers 1021, 1026 in accordance with the flowpatterns as shown in FIG. 14 during fabrication of the i-type layer bymicrowave plasma CVD.

For the thus fabricated photovoltaic element, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Element No.Example 107-5. The results indicated that the open-circuit voltage andthe fill factor in the initial characteristics, the low illuminancecharacteristic, and the durability characteristic of Element No. Example107-5 were 1.02 times, 1.03 times, 1.09 times, and 1.07 times better,respectively, than those in Element No. Comparative Example 93-5.

Further, the composition analysis in the layer thickness direction of Siatoms and Ge atoms in the i-type layer formed by microwave plasma CVD inElement No. Example 107-5 and Comparative Example 93-5 was performed inthe same manner as the previous composition analysis. It was found thatthe photovoltaic element in Element No. Example 107-5 has a minimumvalue of bandgap at a position shifted toward the interface between thep-type layer and the i-type layer, away from the central position of thei-type layer, while the photovoltaic element in Comparative Example 93-5has a minimum value of bandgap at a position shifted toward theinterface between the n-type layer and the i-type layer, away from thecentral position of the i-type layer.

For comparison, a photovoltaic element was fabricated (Element No.Example 107-15) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of the photovoltaic element in Element No. Example107-5, except that BF₃ (2000 ppm)/H₂ gas and PH₃ (2000 ppm)/H₂ gas werenot flowed during fabrication of the i-type layer by microwave plasmaCVD.

For the thus fabricated photovoltaic element, the initialcharacteristics, the low illuminance characteristic, and the durabilitycharacteristic were measured in the same manner as in Element No.Example 107-5. From the results, it was found that the photovoltaicelement of Element No. Example 107-5 was superior to that of Element No.Example 107-15, in that the open-circuit voltage and the fill factor ofthe initial characteristics, the low illuminance characteristic, and thedurability characteristic were 1.02 times, 1.03 times, 1.09 times, and1.07 times better.

Composition analysis of the photovoltaic element of Element No. Example107-5 was performed using a secondary ion mass spectrometer, and it wasconfirmed that B and P atoms were contained in the i-type layer.

Then, photovoltaic elements were fabricated (Element No. Examples 107-16to 107-20 and Comparative Example 93-6) by forming a reflecting layer, areflection multiplying layer, an n-type layer, an i-type layer, a p-typelayer, a transparent electrode and a collector electrode on a substrateunder the same conditions as those of the photovoltaic element inElement No. Example 107-5, except that the SiH₄ gas flow and the RFdischarge power were as indicated in Table 67 during formation of thei-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 107-5. Theresults are listed in Table 67. As seen from Table 67, a photovoltaicelement having excellent characteristics can be fabricated by making thei-type layer by RF plasma CVD at a deposition rate of 2 nm/sec or less.

Then, photovoltaic elements were fabricated (Element No. Examples 107-21to 107-23 and Comparative Examples 93-7 to 93-8) by forming a reflectinglayer, a reflection multiplying layer, an n-type layer, an i-type layer,a p-type layer, a transparent electrode, and a collector electrode onsubstrates under the same conditions as in Element No. Example 107-5,except that the layer thickness of the i-type layer was as indicated inTable 68 during fabrication of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Element No. Example 107-5. Theresults are listed in Table 68. As seen from Table 68, the photovoltaicelements (Element Nos. Example 107-21 to 107-23) provided with thei-type layer formed by RF plasma CVD and having a layer thickness of 30nm or less have excellent characteristics.

Then, photovoltaic elements were fabricated (Element No. Example 107-24to 107-27) by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as the photovoltaic element in Element No. Example 107-5,except that the RF discharge power was as indicated in Table 69 duringformation of the i-type layer by RF plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Element No. Example 107-5. The results are listed inTable 69. As seen in Table 69, a photovoltaic element having a greatervalue of half-width of a peak of 2000⁻¹ in the infrared absorptionspectrum divided by the height of peak in the peak in the i-type layerformed by RF plasma CVD has better characteristics.

From the above results, it has been found that the photovoltaic elementsof the present invention have better characteristics then theconventional photovoltaic elements. The photovoltaic elements of thepresent invention have been fabricated by a process wherein an i-typelayer is formed by microwave plasma CVD at an internal pressure of 50mTorr less by applying to the source gas a lower microwave energy and ahigher RF energy than the microwave energy necessary to decompose 100%of the source gas and a 30 nm or less thick i-type layer formed by RFplasma CVD is deposited at a dependent rate of 2 nm/sec or less. Thebandgap smoothly changes in the direction of layer thickness, and theminimum value of bandgap occurs at a position shifted toward theinterface between the p-type layer and the i-type layer, away from thecentral position of the i-type layer, wherein a valence electron controlagent serving as a donor and an acceptor is doped in the i-type layer.Thus, the effects of the present invention have been demonstrated.

Example 108

Photovoltaic elements (Element No. Examples 108-1 to 108-8) werefabricated in such a manner as to form a reflecting layer, a reflectionmultiplying layer, an n-type layer, an i-type layer, a p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as Element No. Example 107-5, except that after theSiH₄ gas flow nd the GeH₄ gas flow were regulated by mass flowcontrollers 1021, 1026 in accordance with the flow patterns as shown inFIG. 14, as conducted in Example 1. The SiH₄ gas flow was maintained at200 sccm and the GeH₄ gas flow at 1 sccm, and the region of the maximumbandgap had a layer thickness as indicated in Table 70, in making thei-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 107. The results are listed in Table 70. Aswill be seen from Table 70, the photovoltaic elements (Element No.Examples 108-1 to 108-7) having a layer thickness of 1 to 30 nm in theregion of the maximum bandgap exhibit better characteristics, wherebythe effects of the present invention have been evidenced.

Example 109

A photovoltaic element (Element No. Example 109) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except for using a cylinder of AsH₃ /H₂ gas insteadof PH₃ (2000 ppm)/H₂ gas, at a flow rate of 0.2 sccm for the i-typelayer formed by microwave plasma CVD, and 0.5 sccm for the i-type layerformed by RF plasma CVD, during deposition of the i-type layers bymicrowave plasma CVD and RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107, and the results wereequivalent to those of Element No. Example 107-5.

Example 110

A photovoltaic element (Element No. Example 110) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except that the BF₃ (2000 pm)/H₂ gas flow and the PH₃(2000 ppm)/H₂ gas flow were regulated in accordance with the flowpatterns as shown in FIGS. 41 and 42 by the mass flow controllers 1027,1028, during formation of the i-type layer by microwave plasma CVD. TheBF₃ (2000 ppm)/H₂ gas flow and the PH₃ (2000 ppm)/H₂ gas flow were 0.06sccm and 2 sccm, during formation of the i-type layer by RF plasma CVD.

For the photovoltaic element, the initial characteristics, the lowilluminance characteristic and the durability characteristic weremeasured in the same manner as in the Example 107, and the results wereequivalent to those of Element No. Example 107-5.

Also, the distribution of B and P atoms in the i-type layer of thephotovoltaic element was analyzed using a secondary ion massspectrometer. The results are shown in FIGS. 43 and 44. From the aboveresults, the effects of the present invention were evidenced.

Example 111

A photovoltaic element (Element No. Example 111) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except for using a cylinder of NO/He gas 1079 at aflow rate of 0.5 sccm for the i-type layer formed by microwave plasmaCVD and 0.05 sccm for the i-type layer formed by RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107, and the results wereequivalent to those of Element No. Example 107-5.

Also, composition analysis of the photovoltaic element of the Example111 was performed using a secondary ion mass spectrometer, and O and Natoms were confirmed in the i-type layer.

Example 112

A photovoltaic element (Element No. Example 112) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except for using a cylinder of Si₂ H₆ gas at a flowrate of 40 sccm, regulated by a mass flow controller 1021 in accordancewith the flow pattern as shown in FIGS. 25A and 25B, during formation ofthe i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107, and the results wereequivalent to those of Element No. Example 107-5.

Also, the distribution in the layer thickness direction of Si andhydrogen atoms in the i-type layer of the photovoltaic element wasanalyzed using a secondary ion mass spectrometer (IMS-3F manufactured byCAMECA), resulting in the same tendency as in FIGS. 25A and 25B.

From the above results, it has been found that the photovoltaic elementin which the content of hydrogen atoms changes in correspondence withthe content of Si atoms is improved in performance whereby the effectsof the present invention have been evidenced.

Example 113

Photovoltaic elements (Element No. Examples 113-1 to 113-5) werefabricated by forming a reflecting layer, a reflection multiplyinglayer, an n-type layer, an i-type layer, a p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as Element No. Example 107-5, except that the distancebetween the mixing point of SiH₄ gas and GeH₄ gas and the depositionchamber 1001 in the source gas supply unit 1020 was set to the values inTable 71.

For the fabricated photovoltaic elements, the initial characteristics,the low illuminance characteristics, and the durability characteristicwere measured in the same manner as in the Example 107. The results arelisted in Table 71. As seen from Table 71, by making the distancebetween the mixing point of SiH₄ gas and GeH₂ gas and the depositionchamber 1001 equal to or less than 5 m, a photovoltaic element havingfurther improved characteristics can be obtained.

Example 114

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Examples 107-5 and 107-15, whereby a solar cell modulewas fabricated using this photovoltaic element, and an analog clock witha circuit configuration as shown in FIG. 28 was made using the solarcell module as a power source.

The analog clocks as fabricated were installed on a wall within a room,and the analog clock using Element No. Example 107-5 exhibited betterperformance than the analog clock using Element No. Example 107-15.

Example 115

A photovoltaic element (Element No. Example 115) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass controllers 1021, 1026 in accordance with theflow patterns as shown in FIG. 26 during fabrication of the i-type layerby microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured as in Example 107, and the results were equivalent tothose of Element No. Example 107-5, whereby the effects of the presentinvention were demonstrated.

Example 116

A photovoltaic element (Element No. Example 116) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except for using a cylinder of B₂ H₆ gas diluted to2000 ppm with H₂ gas (B₂ H₆ (2000 ppm)/H₂ gas), instead of BF₃ /H₂ gas,at a flow rate of 1 sccm during formation of the i-type layer bymicrowave plasma CVD, and 0.05 sccm during formation of the i-type layerby RF plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristics, and the durability characteristicwere measured as in Example 107, and the results were equivalent tothose of Element No. Example 107-5, whereby the effects of the presentinvention were evidenced.

Example 117

A photovoltaic element (Element No. Example 117) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except that the flow rate of NO/He gas was regulatedby mass flow controller 1029 in accordance with the flow pattern asshown in FIGS. 33A and 33B, during formation of the i-type layer bymicrowave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 107, and the resultswere equivalent to those of Element No. Example 107-5.

Also, the distribution in the layer thickness direction of N and O atomsin the i-type layer of the photovoltaic element was analyzed using asecondary ion mass spectrometer, resulting in the same tendency as inFIGS. 33A and 33B. From the above results, the effects of the presentinvention were demonstrated.

Example 118

A photovoltaic element (Element No. Example 118) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except that the flow rates of SiH₄ gas and GeH₄ gaswere regulated by mass flow controllers 1021, 1026 in accordance withthe flow patterns as shown in FIG. 37, and the RF plasma CVD i-typelayer was formed under the fabrication conditions of Table 60 after theformation of i-type layer formed by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107, and the results wereequivalent to Element No. Example 107-5, whereby the effects of thepresent invention were evidenced.

Example 119

A photovoltaic element (Element No. Example 119) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as Example115, except that RF bias power source 1011 was set at 250 mW/cm³, andthe DC bias was set via a coil at 50 V for application to bias rod 1012during fabrication of the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 115, and the results wereequivalent to those of the Example 115, whereby the effects of thepresent invention were evidenced.

Example 120

A photovoltaic element (Element No. Example 120) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except for using a cylinder of D₂ gas (not shown),instead of H₂ at flow rate of 300 sccm during formation of the i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in the Example 107, and the resultswere equivalent to those of Element No. Example 107-5.

Also, composition analysis of the photovoltaic element was performedusing a secondary ion mass spectrometer, and it was confirmed that Datoms were contained in the i-type layer, whereby the effects of thepresent invention were evidenced.

Example 121

A photovoltaic element (Element No. Example 121) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as ElementNo. Example 107-5, except that DC bias power source 1011 was changed ata constant rate from 50 V to 80 V when shutter 1013 was opened duringformation of the n-type layer.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107, and the results wereequivalent to those of Element No. 107-5, whereby the effects of thepresent invention were evidenced.

Example 122

A photovoltaic element (Element No. Example 122-1) was fabricated byforming an n-type layer and a p-type layer under the same conditions asExample 102, and the other layers were formed under the same conditionsas Element No. Example 107-5.

A photovoltaic element (Element No. Example 122-2) was fabricated byforming a reflecting layer, a reflection multiplying layer, an n-typelayer, an i-type layer, a p-type layer, a transparent electrode, and acollector electrode on a substrate under the same conditions as those ofExample 122-1, except that BF₃ (2000 ppm)/H₂ gas and PH₃ (2000 ppm)/H₂gas were not used in forming the i-type layer by microwave plasma CVD.

For the fabricated photovoltaic elements (Element No. Examples 122-1 to122-2), the initial characteristics, the low illuminance characteristic,and the durability characteristic were measured in the same manner as inExample 107. From the results, it was determined that the photovoltaicelement of Element No. 122-1 was 1.03 times better in the open-circuitvoltage and 1.04 times better in the fill factor of the initialcharacteristics, 1.09 times better in the photovoltaic conversionefficiency of the low illuminance characteristic, and 1.08 times betterin the decrease in the photovoltaic conversion efficiency (thedurability characteristics) than the photovoltaic element of Element No.Example 122-1, whereby the effects of the present invention weredemonstrated.

Example 123

A photovoltaic element (Element No. Example 123-1) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe conditions as listed in Table 72, with the same method as theExample 107.

A photovoltaic element (Element No. Example 123-2) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, atransparent electrode, and a collector electrode on a substrate underthe same conditions as Example 123-1, except that BF₃ (2000 ppm)/H₂ gasand PH₃ (2000 ppm)/H₂ gas were not used in forming the first i-typelayer by microwave plasma CVD.

For the fabricated photovoltaic elements (Element No. Example 123-1 to123-2), the initial characteristics, the low illuminance characteristic,and the durability characteristic were measured in the same manner as inExample 107. From the results, it was determined that the photovoltaicelement of Element No. Example 123-1 was 1.04 times better in theopen-circuit voltage and 1.03 times better in the fill factor of theinitial characteristics, 1.08 times better in the photovoltaicconversion efficiency of the low illuminance characteristic, and 1.09times better in the decrease in the photovoltaic conversion efficiency(the durability characteristic) than the photovoltaic element of ElementNo. Example 123-2, whereby the effects of the present invention weredemonstrated.

Example 124

A photovoltaic element (Element No. Example 124-1) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as listed in Table 73, with the same method as Example 107.

A photovoltaic element (Element No. Example 124-2) was fabricated byforming a reflecting layer, a reflection multiplying layer, a firstn-type layer, a first i-type layer, a first p-type layer, a secondn-type layer, a second i-type layer, a second p-type layer, a thirdn-type layer, a third i-type layer, a third p-type layer, a transparentelectrode, and a collector electrode on a substrate under the sameconditions as those of Example 124-1, except that BF₃ (2000 ppm)/H₂ gasand PH₃ (2000 ppm)/H₂ gas were not used in forming the first and secondi-type layers by microwave plasma CVD.

For the fabricated photovoltaic elements (Element No. Examples 124-1 to124-2), the initial characteristics, the low illuminance characteristic,and the durability characteristic were measured in the same manner as inExample 107. Form the results, it was determined that the photovoltaicelement of Element No. Example 124-1 was 1.03 times better in theopen-circuit voltage and 1.04 times better in the fill factor of theinitial characteristics, 1.08 times better in the photovoltaicconversion efficiency of the low illuminance characteristic, and 1.07times better in the decrease in the photovoltaic conversion efficiency(the durability characteristic) than the photovoltaic element of ElementNo. Example 124-2, whereby the effects of the present invention weredemonstrated.

Example 125

A photovoltaic element of the present invention was fabricated using amultiple chamber separation-type deposition apparatus as shown in FIG.22. The photovoltaic element (Element No. Example 125) was made inaccordance with the procedure of Example 105 under the same conditionsas those of Example 123.

For the fabricated photovoltaic element, the initial characteristics,the low illuminance characteristic, and the durability characteristicwere measured in the same manner as in Example 107. From the results, itwas found that the photovoltaic element was 1.01 times better inopen-circuit voltage and 1.02 times better in fill factor of the initialcharacteristics, 1.02 times better in photovoltaic conversion efficiencyof the low illuminance characteristic, and 1.03 times better in decreasein the photovoltaic conversion efficiency (durability characteristic)than Element No. Example 123. The photovoltaic device of the presentinvention had better characteristics by fabricating it in a multiplecheer separation-type deposition apparatus, whereby the effects of thepresent invention were evidenced.

Example 126

A photovoltaic element was fabricated under the same conditions as thoseof Element No. Examples 123-1 to 123-2, whereby a solar cell module wasmade using the photovoltaic element, and a car-mounted ventilation fanhaving a circuit configuration as shown in FIG. 28 was produced usingthe solar cell module.

A car mounted with ventilation fans utilizing Element No. Examples 123-1to 123-2 was left in an idling state with the engine running for 168hours, and then left in sunny weather with the ventilation fan workingand with the engine stopped, whereafter the temperature within the carwas measured. As a result, the car-mounted cooling fan of Element No.Example 123-1 achieved an interior temperature three degrees lower thanthe fan of Element No. Example 123-2.

                                      TABLE 1                                     __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                           Microwave                                                                     discharge                                                                     electric          Substrate                                   Layer  Gas used and                                                                           power       Pressure                                                                            temperature                                                                          Layer                                name   flow (sccm)                                                                            (mW/Cm.sup.3)                                                                       Bias  (mTorr)                                                                             (°C.)                                                                         thickness                     __________________________________________________________________________                                                    (nm)                          Fabrication                                                                          n-type SiH.sub.4                                                                          50  130   DC    10    350    10                            conditions                                                                           layer  PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    i-type SiH.sub.4, See FIG.                                                                    170   RF    See Table 2                                                                         350    300                                  layer by                                                                             23A            (mW/cm.sup.3)                                           microwave                                                                            H.sub.2                                                                            500       DC OV                                                   plasma GeH.sub.4 See FIG.                                                     CVD    23A                                                                    i-type SiH.sub.4                                                                          8   RF 120      500   300    10                                   layer by                                                                             H.sub.2                                                                            100 (mW/cm.sup.2)                                                 RF plasma                                                                     CVD                                                                           p-type SiH.sub.4                                                                          10  250         25    300    10                                   layer  H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to                                                                   1%)                                                             __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminun (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________                              Low    Durability                                          Pressure           illuminance                                                                          characteristic                                      within             characteristic                                                                       Decrease in                                         deposition                                                                          Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       chamber                                                                             Open-circuit conversion                                                                           conversion                                   Element No.                                                                          (mTorr)                                                                             voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                   __________________________________________________________________________    Example 1-1                                                                          0.5   1.02   1.02  1.06   1.05                                         Example 1-2                                                                           1    1.02   1.02  1.06   1.05                                         Example 1-3                                                                           2    1.02   1.02  1.06   1.06                                         Example 1-4                                                                           5    1.03   1.03  1.08   1.07                                         Example 1-5                                                                          10    1.03   1.03  1.07   1.08                                         Example 1-6                                                                          20    1.03   1.02  1.05   1.08                                         Example 1-7                                                                          50    1.02   1.02  1.05   1.06                                         Comparative                                                                          100   1.00   1.00  1.00   1.00                                         Example 1-1                                                                   __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 11.

                                      TABLE 3                                     __________________________________________________________________________                     Decomposition efficiency of source gas at each                                microwave                                                    Gas flow rate (sccm)                                                                           electric power (W/cm.sup.3) (%)                              Sample No.                                                                          SiH.sub.4                                                                           GeH.sub.4                                                                          0.1  0.2  0.3  0.4   0.5                                     __________________________________________________________________________    1-1   200    1   24   45   68   93    100                                     1-2   170   20   25   48   73   97    100                                     1-3   140   40   27   51   76   99    100                                     1-4   110   60   28   53   81   100   100                                     1-5    80   80   31   58   88   100   100                                     __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________                                Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                       Microwave                                                                             Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                     electric power                                                                        Open-circuit conversion                                                                           conversion                                 Element No.                                                                          (W/cm.sup.3)                                                                          voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                 __________________________________________________________________________    Example 1-8                                                                          0.1     1.02   1.02  1.08   1.07                                       Example 1-9                                                                          0.2     1.04   1.03  1.07   1.08                                       Example 1-10                                                                         0.3     1.02   1.02  1.07   1.06                                       Comparative                                                                          0.4     1.00   1.01  1.01   1.01                                       Example 1-2                                                                   Comparative                                                                          0.5     1.00   1.00  1.00   1.00                                       Example 1-3                                                                   __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 13.

                                      TABLE 5                                     __________________________________________________________________________                              Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                               Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       RF bias                                                                             Open-circuit conversion                                                                           conversion                                   Element No.                                                                          (mW/cm.sup.3)                                                                       voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                   __________________________________________________________________________    Comparative                                                                          150   1.00   1.00  1.00   1.00                                         Example 1-4                                                                   Example 1-11                                                                         200   1.02   1.01  1.05   1.06                                         Example 1-12                                                                         250   1.03   1.02  1.06   1.07                                         Example 1-13                                                                         300   1.03   1.03  1.06   1.07                                         Example 1-14                                                                         350   1.02   1.02  1.07   1.07                                         __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 14.

                  TABLE 6                                                         ______________________________________                                        Gas flow rate (sccm)                                                                             Bandgap  Composition ratio                                 Sample No.                                                                            SiH.sub.4 GeH.sub.4                                                                              (eV)   Si     Ge                                   ______________________________________                                        1-6     200        1       1.71   100    1                                    1-7     170       20       1.60   8.7    1                                    1-8     140       40       1.52   3.3    1                                    1-9     110       60       1.45   1.9    1                                     1-10    80       80       1.38   1.1    1                                     1-11                      1.69                                               ______________________________________                                    

                                      TABLE 7                                     __________________________________________________________________________                                           Durability                                                     Initial Low    characteristic                                Flow rate        characteristics                                                                       illuminance                                                                          Decrease in                            Element No.                                                                          of SiH.sub.4                                                                        RF    Deposition                                                                         Open-   Photoelectric                                                                         photoelectric                         (Sample                                                                              gas   power rate circuit                                                                           Fill                                                                              conversion                                                                            conversion                            No.)   (sccm)                                                                              (mW/cm.sup.2)                                                                       (nm/sec)                                                                           voltage                                                                           factor                                                                            efficiency                                                                            efficiency                            __________________________________________________________________________    Example                                                                               1     15    0.05                                                                              1.03                                                                              1.04                                                                              1.08   1.06                                   1-15 (1-12)                                                                   Example                                                                               2     30   0.1  1.03                                                                              1.03                                                                              1.08   1.06                                   1-16 (1-13)                                                                   Example                                                                              10    150   0.5  1.03                                                                              1.03                                                                              1.07   1.07                                   1-17 (1-14)                                                                   Example                                                                              20    300   1.1  1.02                                                                              1.03                                                                              1.05   1.07                                   1-18 (1-15)                                                                   Example                                                                              40    500   2.0  1.02                                                                              1.03                                                                              1.05   1.06                                   1-19 (1-16)                                                                   Example                                                                              60    1000  2.8  1.00                                                                              1.00                                                                              1.00   1.00                                   1-16 (1-17)                                                                   __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 16.

                                      TABLE 8                                     __________________________________________________________________________                               Low    Durability                                         Layer               illuminance                                                                          characteristic                                     thickness of        characteristic                                                                       Decrease in                                        i-type layer                                                                         Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                      by RF plasma                                                                         Open-circuit conversion                                                                           conversion                                  Element No.                                                                          CVD (nm)                                                                             voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Comparative                                                                           0     1.00   1.00  1.00   1.00                                        Example 1-7                                                                   Example 1-20                                                                          1     1.02   1.02  1.02   1.04                                        Example 1-21                                                                          3     1.03   1.02  1.04   1.06                                        Example 1-5                                                                          10     1.03   1.03  1.07   1.07                                        Example 1-22                                                                         30     1.02   1.02  1.05   1.07                                        Comparative                                                                          50     1.01   1.00  1.02   1.02                                        Example 1-8                                                                   __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 17.

                                      TABLE 9                                     __________________________________________________________________________                  Value of                  Durability                                          half-width         Low    characteristic                                      at a peak of       illuminance                                                                          Decrease in                           Element No.                                                                          RF discharge                                                                         2000 cm.sup.-1                                                                      Initial characteristics                                                                    Photoelectric                                                                        photoelectric                         (Sample                                                                              power  divided by                                                                          Open-circuit conversion                                                                           conversion                            No.)   (mW/cm.sup.2)                                                                        peak height                                                                         voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                            __________________________________________________________________________    Example                                                                               90    1.31  1.02   1.03  1.04   1.06                                  1-23 (1-18)                                                                   Example 1-5                                                                          120    1.16  1.02   1.02  1.05   1.05                                  (1-19)                                                                        Example                                                                              150    1.07  1.01   1.01  1.04   1.05                                  1-24 (1-20)                                                                   Example                                                                              180    0.95  1.00   1.01  1.02   1.01                                  1-25 (1-21)                                                                   Example                                                                              210    0.88  1.00   1.00  1.00   1.00                                  1-26 (1-22)                                                                   (1-23)        1.0                                                             __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 126. The value      of halfwidth divided by height is relative value with reference to Sample     No. 123.                                                                 

                                      TABLE 10                                    __________________________________________________________________________           Layer               Low    Durability                                         thickness of        illuminance                                                                          characteristic                                     the region at       characteristic                                                                       Decrease in                                        maximum                                                                              Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                      bandgap                                                                              Open-circuit conversion                                                                           conversion                                  Element No.                                                                          (nm)   voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Example 2-1                                                                           1     1.01   1.02  1.03   1.02                                        Example 2-2                                                                           2     1.02   1.03  1.05   1.04                                        Example 2-3                                                                           3     1.03   1.03  1.06   1.06                                        Example 2-4                                                                           5     1.03   1.03  1.05   1.07                                        Example 2-5                                                                          10     1.04   1.03  1.05   1.06                                        Example 2-6                                                                          20     1.03   1.02  1.04   1.05                                        Example 2-7                                                                          30     1.02   1.02  1.04   1.04                                        Example 2-8                                                                          50     1.00   1.00  1.00   1.00                                        __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 28.            

                                      TABLE 11                                    __________________________________________________________________________           Distance             Low    Durability                                        between mixing       illuminance                                                                          characteristic                                    point of gases       characteristic                                                                       Decrease in                                       and deposition                                                                        Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                     chamber Open-circuit conversion                                                                           conversion                                 Element No.                                                                          (m)     voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                 __________________________________________________________________________    Example 7-1                                                                          1       1.03   1.04  1.05   1.07                                       Example 7-2                                                                          2       1.02   1.03  1.05   1.06                                       Example 7-3                                                                          3       1.02   1.03  1.03   1.05                                       Example 7-4                                                                          5       1.02   1.02  1.03   1.03                                       Example 7-5                                                                          8       1.00   1.00  1.00   1.00                                       __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 75.            

                                      TABLE 12                                    __________________________________________________________________________    Substrate     SUS430BA 50 mm square 1 mm thick                                Reflecting layer                                                                            Silver (Ag) thin film 100 nm                                    Reflection multiplying layer                                                                Zinc oxide (ZnO) thin film 1 μm                              __________________________________________________________________________                          RF                                                                            discharge                                                             gas used                                                                              electric       Layer                                                  and flow                                                                              power                                                                              Pressure                                                                           Substrate                                                                          thickness                                       Layer name                                                                           (sccm)  (W/cm.sup.3)                                                                       (Torr)                                                                             (C.°)                                                                       (nm)                                     __________________________________________________________________________    Fabrication                                                                          n-type Si.sub.2 H.sub.6                                                                   3  0.12 1    350  10                                       conditions                                                                           layer  PH.sub.3 /H.sub.2                                                                  5                                                          of layer      (diluted                                                                      to 1%)                                                                        H.sub.2                                                                            50                                                                i-type Same as Element No. Example 1-5                                        layer                                                                         p-type SiH.sub.4                                                                          0.5                                                                              2    1    200   5                                              layer  H.sub.2                                                                            100                                                                      BF.sub.3 /H.sub.2                                                                  1                                                                       (diluted                                                                      to 1%)                                                           __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 13                                    __________________________________________________________________________    Substrate      SUS430BA 50 mm square 1 mm thick                               Reflecting layer                                                                             Silver (Ag) thin film 100 nm                                   Reflection multiplying layer                                                                 Zinc Oxide (ZnO) thin film 1 μm                             __________________________________________________________________________                          Microwave                                                                     discharge                                                                     electric          Substrate                                                                            Layer                                 Layer gas used and                                                                           power       Pressure                                                                            temperature                                                                          thickness                             name  flow (sccm)                                                                            (mW/Cm3)                                                                            Bias  (mTorr)                                                                             (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          First Si.sub.2 H.sub.6                                                                   1   RF          1500  370    20                             conditions                                                                           n-type                                                                              H.sub.2                                                                            50  80                                                      of layer                                                                             layer PH.sub.3 /H.sub.2                                                                  1   (mW/cm.sup.2)                                                        (diluted to                                                                   1%)                                                                     First SiH.sub.4                                                                              Microwave                                                                           RF 350                                                                               10   350    300                                   i-type                                                                              See FIG. 35                                                                            170   (mW/cm.sup.3)                                            layer by                                                                            H.sub.2                                                                            500 (mW/cm.sup.3)                                                                       DC OV                                                    microwave                                                                           GeH.sub.4                                                               plasma                                                                              See FIG. 35                                                             CVD                                                                           First SiH.sub.4                                                                          8   RF           500  350    10                                    i-type                                                                              H.sub.2                                                                            100 120                                                            layer by                                                                            BF.sub.3 /H.sub.2                                                                  1   (mW/cm.sup.2)                                                  RF plassma                                                                          (2000 ppm)                                                              CVD   PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                              First SiH.sub.4                                                                          0.05                                                                              RF          2000  250    10                                    p-type                                                                              H.sub.2                                                                            100 1.5                                                            layer BF.sub.3 /H.sub.2                                                                      (mW/cm.sup.2)                                                        (diluted to                                                                   1%)                                                              Fabrication                                                                          Second                                                                              Si.sub.2 H.sub.6                                                                   1   RF          1500  300    10                             conditions                                                                           n-type                                                                              H.sub.2                                                                            50  80                                                      of layer                                                                             layer PH.sub.3 /H.sub.2                                                                  1   (mW/cm.sup.2)                                                        (diluted to                                                                   1%)                                                                     Second                                                                              SiH.sub.4                                                                          200 Microwave                                                                           RF      5   300    150                                   i-type                                                                              H.sub.2                                                                            700 170   250                                                      layer          (mW/cm.sup.3)                                                                       (mW/cm.sup.3)                                                                 DC OV                                                    Second                                                                              SiH.sub.4                                                                          0.05                                                                              RF          2000  200     5                                    p-type                                                                              H.sub.2                                                                            100 1.5                                                            layer BF.sub.3 /H.sub.2                                                                  5   (mW/cm.sup.2)                                                        (diluted to                                                                   1%)                                                              __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 14                                    __________________________________________________________________________    Substrate      SUS430BA 50 mm square 1 mm thick                               Reflecting layer                                                                             Silver (Ag) thin film 100 nm                                   Reflection multiplying layer                                                                 Zinc Oxide (ZnO) thin film 1 μm                             __________________________________________________________________________                          Microwave                                                                     discharge                                                                     electric          Substrate                                                                            Layer                                 Layer Gas used and                                                                           power       Pressure                                                                            temperature                                                                          thickness                             name  flow (sccm)                                                                            (mW/cm.sup.3)                                                                       Bias  (mTorr)                                                                             (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          First SiH.sub.4                                                                          50  130   DC 50V                                                                              10    350    10                             conditions                                                                           n-type                                                                              PH.sub.3 /H.sub.2                                                                  200                                                         of layer                                                                             layer (diluted to                                                                   1%)                                                                     First SiH.sub.4                                                                              170   RF 350                                                                              10    350    250                                   i-type                                                                              See FIG. 36A   (mW/cm.sup.3)                                            layer by                                                                            H.sub.2                                                                            500       DC OV                                                    microwave                                                                           GeH.sub.4                                                               plasma                                                                              See FIG. 36A                                                            CVD                                                                           First SiH.sub.4                                                                          8   RF 120      500   350    10                                    i-type                                                                              H.sub.2                                                                            100 (mW/cm.sup.2)                                                  layer by                                                                            BF.sub.3 /H.sub.2                                                                  0.5                                                                RF plasma                                                                           (2000 ppm)                                                              CVD   PH.sub.3 /H.sub.2                                                                  0.06                                                                     (2000 ppm)                                                              First SiH.sub.4                                                                          10  250         25    350    10                                    p-type                                                                              H.sub.2                                                                            700                                                                layer BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to                                                                   1%)                                                              Fabrication                                                                          Second                                                                              SiH.sub.4                                                                          50  130   DC 50V                                                                              10    350    10                             conditions                                                                           n-type                                                                              PH.sub.3 /H.sub.2                                                                  200                                                         of layer                                                                             layer (diluted to                                                                   1%)                                                                     Second                                                                              SiH.sub.4                                                                              210   RF 280                                                                              10    350    200                                   i-type                                                                              See FIG. 36B   (mW/cm.sup.3)                                            layer by                                                                            H.sub.2                                                                            500       DC OV                                                    microwave                                                                           GeH.sub.4                                                               plasma                                                                              See FIG. 36B                                                            CVD                                                                           Second                                                                              SiH.sub.4                                                                          8   RF          500   350    10                                    i-type                                                                              H.sub.2                                                                            100 120                                                            layer by                                                                            BF.sub.3 /H /H.sub.2                                                               2   (mW/cm.sup.3)                                                  RF plasma                                                                           (2000 ppm)                                                              CVD   PH.sub.3 /H.sub.2                                                                  0.03                                                                     (2000 ppm)                                                              Second                                                                              SiH.sub.4                                                                          10  250         25    350    10                                    p-type                                                                              H.sub.2                                                                            700                                                                layer PF.sub.3 /H.sub.2                                                                  30  L,1 Fabrication                                                Third SiH.sub.4                                                                          50  130   DC 50V                                                                              10    350    10                                    conditions                                                                          n-type                                                                             PH.sub.3 /H.sub.2                                                                 200                                                     of layer                                                                             layer (diluted to                                                                   1%)x                                                                    Third SiH.sub.4                                                                          200 150   RF 300                                                                               5    300    100                                   i-type                                                                              H.sub.2                                                                            700       (mW/cm.sup.3)                                            layer                DC OV                                                    Third SiH.sub.4                                                                          10  250         25    300     5                                    p-type                                                                              H.sub.2                                                                            700                                                                layer BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to                                                                   1%)                                                              __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 15                                    __________________________________________________________________________    Substrate      SUS430BA 50 mm square 1 mm thick                               Reflecting layer                                                                             Silver (Ag) thin film 100 nm                                   Reflection multiplying layer                                                                 Zinc Oxide (ZnO) thin film 1 μm                             __________________________________________________________________________                           Microwave                                                                     discharge                                                                     electric           Substrate                                                                            Layer                                       Gas used and                                                                          power       Pressure                                                                             temperature                                                                          thickness                           Layer name                                                                            flow (sccm)                                                                           (mW/cm.sup.3)                                                                       Bias  (mTorr)                                                                              (°C.)                                                                         (nm)                         __________________________________________________________________________    Fabrication                                                                          n-type layer                                                                          SiH.sub.4                                                                          50 130   DC 50V                                                                              10     350    10                           conditions     H.sub.2                                                                            200                                                       of layer       (diluted to                                                                   1%)                                                                   i-type layer                                                                          SiH.sub.4                                                                             170   RF 350                                                                              Table 16                                                                             350    300                                 by microwave                                                                          See FIG. 23A  (mW/cm.sup.3)                                           plasma CVD                                                                            H.sub.2                                                                            500      DC OV                                                           GeH.sub.4                                                                     See FIG.                                                                      23A                                                                           (diluted to                                                                   1%)                                                                   i-type layer                                                                          SiH.sub.4                                                                          8  RF 120      500    300    10                                  by RF plasma                                                                          H.sub.2                                                                            100                                                                              (mW/cm.sup.2)                                                 CVD                                                                           p-type layer                                                                          SiH4 1  50          25     300    0.5                                 doping layer                                                                          H2   300                                                              B1      BF.sub.3 /H.sub.2                                                                  2                                                                p-type layer                                                                          B.sub.2 H.sub.6 /H.sub.2                                                           100                                                                              50          30     300    0.3                                 doping layer                                                                          (10%)                                                                 A                                                                             p-type layer                                                                          SiH4 1  50          25     300    10                                  doping layer                                                                          H2   300                                                              B2      BF.sub.3 /H.sub.2                                                                  2                                                         __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 16                                    __________________________________________________________________________                                  Low     Durability                                      Pressure              illuminance                                                                           characteristic                                  within                characteristic                                                                        Decrease in                                     deposition                                                                           Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   chamber                                                                              Open-circuit   conversion                                                                            conversion                              Element No.                                                                           (mTorr)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                              __________________________________________________________________________    Example 21-1                                                                          0.5    1.02    1.02   1.05    1.05                                    Example 21-2                                                                          1      1.02    1.02   1.06    1.05                                    Example 21-3                                                                          2      1.02    1.03   1.06    1.06                                    Example 21-4                                                                          5      1.02    1.03   1.07    1.07                                    Example 21-5                                                                          10     1.03    1.03   1.06    1.07                                    Example 21-6                                                                          20     1.03    1.02   1.06    1.06                                    Example 21-7                                                                          50     1.02    1.02   1.05    1.06                                    Comparative                                                                           100    1.00    1.00   1.00    1.00                                    Example 7-1                                                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 71. 

                                      TABLE 17                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                     Microwave                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   power  Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (W/cm.sup.3)                                                                         voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Example 21-8                                                                           0.1    1.02    1.02   1.08    1.07                                   Example 21-9                                                                           0.2    1.02    1.02   1.07    1.08                                   Example 21-10                                                                          0.3    1.01    1.02   1.07    1.06                                   Comparative                                                                            0.4    1.00    1.01   1.02    1.01                                   Example 7-2                                                                   Comparative                                                                            0.5    1.00    1.00   1.00    1.00                                   Example 7-3                                                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 73.                                                              

                                      TABLE 18                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   RF bias                                                                              Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (mW/cm.sup.3)                                                                        voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Comparative                                                                            150    1.00    1.00   1.00    1.00                                   Example 7-4                                                                   Example 21-11                                                                          200    1.02    1.02   1.05    1.06                                   Example 21-12                                                                          250    1.02    1.03   1.07    1.07                                   Example 21-13                                                                          300    1.03    1.02   1.06    1.07                                   Example 21-14                                                                          350    1.02    1.02   1.06    1.06                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 74.                                                              

                                      TABLE 19                                    __________________________________________________________________________                                                          Durability                                                            Low     characteristic                                                        illuminance                                                                           Decrease in                      Flow rate     Deposition                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                    of SiH.sub.4 gas                                                                     RF power                                                                             rate    Open-circuit   conversion                                                                            conversion              Element No.                                                                            (sccm) (mW/cm.sup.2)                                                                        (nm/sec)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency              __________________________________________________________________________    Example 21-15                                                                          1      15     0.05    1.02    1.03   1.06    1.07                    Example 21-16                                                                          2      30     0.1     1.03    1.04   1.06    1.07                    Example 21-17                                                                          10     150    0.5     1.03    1.03   1.07    1.08                    Example 21-18                                                                          20     300    1.1     1.03    1.02   1.07    1.07                    Example 21-19                                                                          40     500    2.0     1.02    1.02   1.06    1.05                    Comparative                                                                            60     1000   2.8     1.00    1.00   1.00    1.00                    Example 7-6                                                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 76.                                                              

                                      TABLE 20                                    __________________________________________________________________________                                    Low     Durability                                     Layer                  illuminance                                                                           characteristic                                 thickness of           characteristic                                                                        Decrease in                                    i-type layer                                                                          Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                  by RF plasma                                                                          Open-circuit   conversion                                                                            conversion                            Element No.                                                                            CVD (nm)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Comparative                                                                            0       1.00    1.00   1.00    1.00                                  Example 7-7                                                                   Example 21-20                                                                          1       1.02    1.01   1.04    1.06                                  Example 21-21                                                                          3       1.02    1.03   1.05    1.07                                  Example 21-5                                                                           10      1.03    1.03   1.07    1.07                                  Example 21-22                                                                          30      1.02    1.02   1.05    1.06                                  Comparative                                                                            50      1.01    1.00   1.01    1.02                                  Example 7-8                                                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 77.                                                              

                                      TABLE 21                                    __________________________________________________________________________                     Value of                      Durability                                      half-width            Low     characteristic                                  at a peak of          illuminance                                                                           Decrease in                             RF discharge                                                                          2000 cm.sup.-1                                                                       Initial characteristics                                                                      Photoelectric                                                                         photoelectric                           power   divided by                                                                           Open-circuit   conversion                                                                            conversion                     Element No.                                                                            (mW/cm.sup.2)                                                                         peak height                                                                          voltage Fill factor                                                                          efficiency                                                                            efficiency                     __________________________________________________________________________    Example 21-23                                                                          90      1.31   1.02    1.02   1.05    1.05                           Example 21-5                                                                           120     1.16   1.02    1.03   1.05    1.05                           Example 21-24                                                                          150     1.07   1.02    1.02   1.04    1.04                           Example 21-25                                                                          180     0.95   1.00    1.01   1.01    1.02                           Example 21-26                                                                          210     0.88   1.00    1.00   1.00    1.00                           __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 2126

                                      TABLE 22                                    __________________________________________________________________________                                      Low     Durability                                  Layer                     illuminance                                                                           characteristic                              thickness of              characteristic                                                                        Decrease in                                 the region at                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               maximum bandgap                                                                          Open-circuit   conversion                                                                            conversion                          Element No.                                                                           (nm)       voltage Fill factor                                                                          efficiency                                                                            efficiency                          __________________________________________________________________________    Example 22-1                                                                          1          1.02    1.02   1.04    1.04                                Example 22-2                                                                          2          1.02    1.03   1.05    1.05                                Example 22-3                                                                          3          1.02    1.03   1.05    1.06                                Example 22-4                                                                          5          1.02    1.03   1.06    1.07                                Example 22-5                                                                          10         1.02    1.02   1.06    1.06                                Example 22-6                                                                          20         1.03    1.02   1.05    1.06                                Example 22-7                                                                          30         1.02    1.01   1.05    1.06                                Example 22-8                                                                          50         1.00    1.00   1.00    1.00                                __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 228.

                                      TABLE 23                                    __________________________________________________________________________            Distance                Low     Durability                                    between mixing          illuminance                                                                           characteristic                                point of gases          characteristic                                                                        Decrease in                                   and deposition                                                                         Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                 chamber  Open-circuit   conversion                                                                            conversion                            Element No.                                                                           (m)      voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Example 27-1                                                                          1        1.02    1.03   1.05    1.07                                  Example 27-2                                                                          2        1.03    1.04   1.06    1.06                                  Example 27-3                                                                          3        1.02    1.03   1.06    1.05                                  Example 27-4                                                                          5        1.02    1.02   1.04    1.05                                  Example 27-5                                                                          8        1.00    1.00   1.00    1.00                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 275.

                                      TABLE 24                                    __________________________________________________________________________                                      Low     Durability                                  Layer                     illuminance                                                                           characteristic                              thickness of              characteristic                                                                        Decrease in                                 the region at                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               maximum bandgap                                                                          Open-circuit   conversion                                                                            conversion                          Element No.                                                                           (nm)       voltage Fill factor                                                                          efficiency                                                                            efficiency                          __________________________________________________________________________    Example 33-1                                                                          0.01       1.02    1.02   1.05    1.06                                Example 33-2                                                                          0.03       1.02    1.03   1.06    1.06                                Example 33-3                                                                          0.1        1.03    1.02   1.07    1.07                                Example 21-5                                                                          0.3        1.02    1.02   1.06    1.06                                Example 33-4                                                                          1          1.02    1.02   1.05    1.04                                Example 33-5                                                                          3          1.00    1.00   1.00    1.00                                __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 335.

                                      TABLE 25                                    __________________________________________________________________________                             Microwave                                                                     discharge      Substrate                                                                             Layer                                        gas used and                                                                            electric power                                                                         Pressure                                                                            temperature                                                                           thickness                            Layer name                                                                            flow (sccm)                                                                             (mW/cm.sup.3)                                                                          (mTorr)                                                                             (°C.)                                                                          (nm)                          __________________________________________________________________________    Fabrication                                                                          n-type layer                                                                          SiH.sub.4                                                                            5  40       30    350     0.5                           conditions                                                                           doping layer                                                                          H.sub.2                                                                              200                                                     of n-type                                                                            B1      PH.sub.3 /H.sub.2 (1%)                                                               20                                                      layer  n-type layer                                                                          PH.sub.3 /H.sub.2 (1%)                                                               300                                                                              50       20    350     0.3                                  doping layer                                                                  A                                                                             n-type layer                                                                          SiH.sub.4                                                                            50 150      15    350     10                                   doping layer                                                                          PH.sub.3 /H.sub.2 (1%)                                                               200                                                            B2                                                                     __________________________________________________________________________

                                      TABLE 26                                    __________________________________________________________________________                             Microwave                                                                     discharge      Substrate                                                                             Layer                                        gas used and                                                                            electric power                                                                         Pressure                                                                            temperature                                                                           thickness                            Layer name                                                                            flow (sccm)                                                                             (mW/cm.sup.3)                                                                          (mTorr)                                                                             (°C.)                                                                          (nm)                          __________________________________________________________________________    Fabrication                                                                          doping layer                                                                          SiH.sub.4                                                                           1   50       25    300     0.3                           conditions                                                                           B1      H.sub.2                                                                             300                                                      of n-type      PF.sub.3 /H.sub.2                                                                   2                                                        layer          (2000 ppm)                                                            doping layer                                                                          B.sub.2 H.sub.6 /H.sub.2                                                            100 50       20    300     0.1                                  A1      (10%)                                                                 doping layer                                                                          SiH.sub.4                                                                           1   50       25    300     0.5                                  B2      H.sub.2                                                                             300                                                                     BF.sub.3 /H.sub.2                                                                   2                                                                       (2000 ppm)                                                            doping layer                                                                          B.sub.2 H.sub.6 /H.sub.2                                                            100 30       30    300     0.2                                  A2      (10%)                                                                 doping layer                                                                          SiH.sub.4                                                                           1   50       25    300     0.5                                  B3      H.sub.2                                                                             300                                                                     PF.sub.3 /H.sub.2                                                                   2                                                                       (2000 ppm)                                                            doping layer                                                                          B.sub.2 H.sub.6 /H.sub.2                                                            200 50       20    300     0.5                                  A3      (10%)                                                                 doping layer                                                                          SiH.sub.4                                                                           1   50       25    300     0.8                                  B4      H.sub.2                                                                             300                                                                     BF.sub.3 /H.sub.2                                                                   2                                                                       (2000 ppm)                                                     __________________________________________________________________________

                                      TABLE 27                                    __________________________________________________________________________    Substrate      SUS430BA 50 mm square 1 mm thick                               Reflecting layer                                                                             Silver (Ag) thin film 100 nm                                   Reflection multiplying layer                                                                 Zinc Oxide (ZnO) thin film 1 μm                             __________________________________________________________________________                            RF discharge   Substrate                                                                             Layer                                         Gas used and                                                                           electric power                                                                         Pressure                                                                            temperature                                                                           thickness                             Layer name                                                                            flow (sccm)                                                                            (W/cm.sup.3)                                                                           (Torr)                                                                              (C.°)                                                                          (nm)                           __________________________________________________________________________    Fabrication                                                                          n-type layer                                                                          Si.sub.2 H.sub.6                                                                   3   0.12     1     350     10                             conditions     PH.sub.3 /H.sub.2                                                                  5                                                         of layer       (diluted to 1%)                                                               H2   50                                                               i-type layer                                                                          Same as Element No. Example 21-5                                      p-type layer                                                                          SiH4 0.03                                                                              2        1     200     0.3                                   doping layer                                                                          H2   100                                                              B1      BF.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                            p-type layer                                                                          B.sub.2 H.sub.6 /H.sub.2                                                           50  3        1     200     0.1                                   doping layer                                                                          (10%)                                                                 A                                                                             p-type layer                                                                          SiH4 0.5 2        1     200     5                                     doping layer                                                                          H2   100                                                              B2      BF.sub.3 /H.sub.2                                                                  10                                                                       (2000 ppm)                                                     __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 28                                    __________________________________________________________________________    Substrate      SUS430BA 50 mm square 1 mm thick                               Reflecting layer                                                                             Silver (Ag) thin film 100 nm                                   Reflection multiplying layer                                                                 Zinc Oxide (ZnO) thin film 1 μm                             __________________________________________________________________________                            Discharge           Substrate                                                                             Layer                                    Gas used and                                                                           electric      Pressure                                                                            temperature                                                                           thickness                        Layer name                                                                            flow (sccm)                                                                            power  Bias   (mTorr)                                                                             (°C.)                                                                          (nm)                      __________________________________________________________________________    Fabrication                                                                          First n-type                                                                          Si.sub.2 H.sub.6                                                                   1   RF 80         1500  370     20                        conditions                                                                           layer   H.sub.2                                                                            50  (mW/cm.sup.2)                                         of layer       PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                       First i-type                                                                          SiH.sub.4                                                                              Microwave                                                                            RF 350 10    350     300                              layer by                                                                              See FIG. 35                                                                            170    (mW/cm.sup.3)                                         microwave                                                                             H.sub.2  (mW/cm.sup.3)                                                                        DC 0 V                                                plasma CVD                                                                            GeH.sub.4                                                                     See FIG. 35                                                                   H.sub.2                                                                            700                                                              First i-type                                                                          SiH4 8   RF 120        500   350     10                               layer by RF                                                                           H2   100 (mW/cm.sup.2)                                                plasma CVD                                                                            BF.sub.3 /H.sub.2                                                                  3                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                            First p-type                                                                          SiH4 0.03                                                                              RF 1          2000  250     0.5                              layer doping                                                                          H2   100 (W/cm.sup.2)                                                 layer B1                                                                              BF.sub.3 /H.sub.2                                                                  6                                                                        (2000 ppm)                                                            First p-type                                                                          B.sub.2 H.sub.6 /H.sub.2                                                           100 RF 2          20    250     0.3                              layer doping                                                                          (10%)    (W/cm.sup.2)                                                 layer A                                                                       First p-type                                                                          SiH4 0.05              2000  250     10                               layer doping                                                                          H2   80                                                               layer B2                                                                              BF.sub.3 /H.sub.2                                                                  25                                                                       (2000 ppm)                                                            Second n-type                                                                         Si.sub.2 H.sub.6                                                                   1   RF 80         1500  300     10                               layer   H.sub.2                                                                            50  (mW/cm.sup.2)                                                        PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                       Second i-type                                                                         SiH.sub.4                                                                          200 Microwave                                                                            RF 250 5     300     150                              layer by                                                                              H.sub.2                                                                            700 130    (mW/cm.sup.3)                                         microwave        (mW/cm.sup.3)                                                                        DC 0 V                                                plasma CVD                                                                    Second p-type                                                                         SiH4 0.05                                                                              RF 1.5        2000  200     5                                layer   H2   80  (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  25                                                                       (diluted to 1%)                                                __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 29                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                           Microwave                                                                     discharge   (mTorr)                                                                            temperature                                                                          thickness                                             electric         Substrate                                                                            Layer                                        Gas used and                                                                           power       Pressure                                                                           temperature                                                                          thickness                             Layer name                                                                           flow (sccm)                                                                            (mW/cm.sup.3)                                                                       Bias  (mTorr)                                                                            (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          First n-                                                                             Si.sub.2 H.sub.4                                                                   50  130   DC    1500 350    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    First i-                                                                             SiH.sub.4                                                                              170   RF 350                                                                              10   300    250                                   type layer                                                                           See FIG. 36A   (mW/cm.sup.3)                                           by     H.sub.2                                                                            500       DC OV                                                   microwave                                                                            GeH.sub.4                                                              plasma CVD                                                                           See FIG. 36A                                                           First i-                                                                             SiH4 8   RF 120      500  350    10                                    type layer                                                                           H2   100 (mW/cm.sup.2)                                                 by RF  BF.sub.3 /H.sub.2                                                                  0.3                                                               plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                             First p-                                                                             SiH4 1    50         25   300    0.5                                   type layer                                                                           H2   300                                                               doping BF.sub.3 /H.sub.2                                                                  3                                                                 layer B1                                                                      First p-                                                                             B.sub.2 H.sub.6 /H.sub.2                                                           100 50          20   300    0.3                                   type layer                                                                           (10%)                                                                  doping                                                                        layer A                                                                       First p-                                                                             SiH4 0.05                                                                               50         25   300    10                                    type layer                                                                           H2   80                                                                doping BF.sub.3 /H.sub.2                                                                  25                                                                layer B2                                                                             (2000 ppm)                                                      __________________________________________________________________________                           Discharge        Substrate                                                                            Layer                                        Gas used and                                                                           electric    Pressure                                                                           temperature                                                                          thickness                             Layer name                                                                           flow *sccm)                                                                            power Bias  (mTorr)                                                                            (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          Second n-                                                                            SiH.sub.4                                                                          50  130   DC    10   300    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    Second i-                                                                            SiH.sub.4                                                                              210   RF 280                                                                              10   350    200                                   type layer                                                                           See FIG. 36A   (mW/cm.sup.3)                                           by     H.sub.2                                                                            500       DC OV                                                   microwave                                                                            GeH.sub.4                                                              plasma CVD                                                                           See FIG. 36A                                                           Second i-                                                                            SiH4 8   RF 120      500  350    200                                   type layer                                                                           H2   100 (W/cm.sup.2)                                                  by RF  BF.sub.3 /H.sub.2                                                                  1                                                                 plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                             Second p-                                                                            SiH4 1    50         25   300    0.1                                   type layer                                                                           H2   300                                                               doping BF.sub.3 /H.sub.2                                                                  1                                                                 layer B1                                                                             (2000 ppm)                                                             Second p-                                                                            B.sub.2 H.sub.6 /H.sub.2                                                           100  50         30   300    0.3                                   type layer                                                                           (10%)                                                                  doping                                                                        layer A                                                                       Second p-                                                                            SiH.sub.4                                                                          1    50         25   300    10                                    type layer                                                                           H.sub.2                                                                            300                                                               doping BF.sub.3 /H.sub.2                                                                  0.5                                                               layer B2                                                                             (2000 ppm)                                                      __________________________________________________________________________                           Discharge        Substrate                                                                            Layer                                        Gas used and                                                                           electric    Pressure                                                                           temperature                                                                          thickness                             Layer name                                                                           fow (sccm)                                                                             power       (mTorr)                                                                            (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          Third n-                                                                             SiH.sub.4                                                                          50  130   DC    10   300    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    Third i-                                                                             SiH.sub.4                                                                          200 150   RF 300                                                                               5   300    100                                   type layer                                                                           H.sub.2                                                                            700       (mW/cm.sup.3)                                                                 DC OV                                                   Third p-                                                                             SiH4 10  250         25   250    5                                     type layer                                                                           H2   600                                                                      BF.sub.3 /H.sub.2                                                                  501                                                                      (diluted to                                                                   1%)                                                             __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 30                                    __________________________________________________________________________                              Low    Durability                                          Pressure           illuminance                                                                          characteristic                                      within             characteristic                                                                       Decrease in                                         deposition                                                                          Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       chamber                                                                             Open-circuit conversion                                                                           conversion                                   Element No.                                                                          (mTorr)                                                                             voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                   __________________________________________________________________________    Example 44-1                                                                         0.5   1.02   1.02  1.06   1.05                                         Example 44-2                                                                          1    1.02   1.03  1.07   1.06                                         Example 44-3                                                                          2    1.02   1.03  1.07   1.06                                         Example 44-4                                                                          5    1.03   1.03  1.08   1.07                                         Example 44-5                                                                         10    1.03   1.03  1.07   1.07                                         Example 44-6                                                                         20    1.02   1.02  1.06   1.08                                         Example 44-7                                                                         50    1.02   1.02  1.05   1.07                                         Comparative                                                                          100   1.00   1.00  1.00   1.00                                         Example 12-1                                                                  __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 121

                                      TABLE 31                                    __________________________________________________________________________                                 Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                       Microwave                                                                             Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                     electric power                                                                        Open-circuit conversion                                                                           conversion                                Element No.                                                                           (W/cm.sup.3)                                                                          voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                __________________________________________________________________________    Example 44-8                                                                          0.1     1.02   1.02  1.08   1.07                                      Example 44-9                                                                          0.2     1.02   1.03  1.09   1.09                                      Example 44-10                                                                         0.3     1.02   1.02  1.07   1.08                                      Comparative                                                                           0.4     1.00   1.01  1.01   1.02                                      Example 12-2                                                                  Comparative                                                                           0.5     1.00   1.00  1.00   1.00                                      Example 12-3                                                                  __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 123

                                      TABLE 32                                    __________________________________________________________________________                               Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                               Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       RF bias                                                                             Open-circuit conversion                                                                           conversion                                  Element No.                                                                           (mW/cm.sup.3)                                                                       voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Comparative                                                                           150   1.00   1.00  1.00   1.00                                        Example 12-4                                                                  Example 44-11                                                                         200   1.02   1.02  1.05   1.04                                        Example 44-12                                                                         250   1.03   1.02  1.05   1.07                                        Example 44-13                                                                         300   1.03   1.03  1.06   1.07                                        Example 44-14                                                                         350   1.03   1.02  1.06   1.05                                        __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 124

                                      TABLE 33                                    __________________________________________________________________________                                            Durability                                                     Initial Low    characteristic                               Flow rate         characteristics                                                                       illuminance                                                                          Decrease in                                  of SiH.sub.4                                                                        RF    Deposition                                                                          Open-   Photoelectric                                                                        photoelectric                         Element                                                                              gas   power rate  circuit                                                                           Curve                                                                             conversion                                                                           conversion                            No.    (sccm)                                                                              (mW/cm.sup.2)                                                                       (nm/sec)                                                                            voltage                                                                           factor                                                                            efficiency                                                                           efficiency                            __________________________________________________________________________    Example                                                                               1     15    0.05 1.03                                                                              1.03                                                                              1.08   1.06                                  44-16                                                                         Example                                                                               2     30   0.1   1.03                                                                              1.03                                                                              1.07   1.07                                  44-17                                                                         Example                                                                              10    150   0.5   1.03                                                                              1.02                                                                              1.07   1.06                                  44-18                                                                         Example                                                                              20    300   1.1   1.02                                                                              1.02                                                                              1.06   1.06                                  44-19                                                                         Example                                                                              40    500   2.0   1.02                                                                              1.02                                                                              1.05   1.06                                  44-20                                                                         Comparative                                                                          60    1000  2.8   1.00                                                                              1.00                                                                              1.00   1.00                                  Example                                                                       12-6                                                                          __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 126

                                      TABLE 34                                    __________________________________________________________________________                                Low    Durability                                         Layer               illuminance                                                                          characteristic                                     thickness of        characteristic                                                                       Decrease in                                        i-type layer                                                                         Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                      by RF plasma                                                                         Open-circuit conversion                                                                           conversion                                 Element No.                                                                           CVD (nm)                                                                             voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                 __________________________________________________________________________    Comparative                                                                            0     1.00   1.00  1.00   1.00                                       Example 12-7                                                                  Example 44-21                                                                          1     1.02   1.02  1.03   1.04                                       Example 44-22                                                                          3     1.02   1.02  1.05   1.06                                       Example 44-5                                                                          10     1.03   1.02  1.07   1.07                                       Example 44-23                                                                         30     1.02   1.02  1.06   1.05                                       Comparative                                                                           50     1.01   1.00  1.02   1.02                                       Example 12-8                                                                  __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 127

                                      TABLE 35                                    __________________________________________________________________________                 Value of                    Durability                                        half-width         Low      characteristic                       at a peak of       illuminance  Decrease in                                   RF discharge 2000 cm.sup.-3                                                                      Initial characteristics                                                                    Photoelectric                                                                          photoelectric                        Element                                                                             power  divided by                                                                          Open-circuit conversion                                                                             conversion                           No.   (mW/cm.sup.2)                                                                        peak height                                                                         voltage                                                                              Fill factor                                                                         efficiency                                                                             efficiency                           __________________________________________________________________________    Example                                                                              90    1.31  1.03   1.02  1.04     1.06                                 44-24                                                                         Example                                                                             120    1.16  1.02   1.02  1.05     1.06                                 44-5                                                                          Example                                                                             150    1.07  1.01   1.01  1.05     1.05                                 44-25                                                                         Example                                                                             180    0.95  1.00   1.01  1.02     1.02                                 44-26                                                                         Example                                                                             210    0.88  1.00   1.00  1.00     1.00                                 44-27                                                                         __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 4427.          

                                      TABLE 36                                    __________________________________________________________________________           Layer               Low    Durability                                         thickness of        illuminance                                                                          characteristic                                     the region at       characteristic                                                                       Decrease in                                        maximum                                                                              Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                      bandgap                                                                              Open-circuit conversion                                                                           conversion                                  Element No.                                                                          (nm)   voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Example 45-1                                                                          1     1.01   1.02  1.03   1.02                                        Example 45-2                                                                          2     1.03   1.03  1.05   1.04                                        Example 45-3                                                                          3     1.03   1.03  1.05   1.06                                        Example 45-4                                                                          5     1.03   1.02  1.05   1.06                                        Example 45-5                                                                         10     1.04   1.02  1.05   1.06                                        Example 45-6                                                                         20     1.04   1.02  1.04   1.06                                        Example 45-7                                                                         30     1.02   1.01  1.04   1.05                                        Example 45-8                                                                         50     1.00   1.00  1.00   1.00                                        __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 458.           

                                      TABLE 37                                    __________________________________________________________________________           Distance             Low    Durability                                        between mixing       illuminance                                                                          characteristic                                    point of gases       characteristic                                                                       Decrease in                                       and deposition                                                                        Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                     chamber Open-circuit conversion                                                                           conversion                                 Element No.                                                                          (m)     voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                 __________________________________________________________________________    Example 50-1                                                                         1       1.03   1.04  1.05   1.07                                       Example 50-2                                                                         2       1.03   1.04  1.05   1.07                                       Example 50-3                                                                         3       1.02   1.03  1.03   1.06                                       Example 50-4                                                                         5       1.02   1.03  1.03   1.04                                       Example 50-5                                                                         8       1.00   1.00  1.00   1.00                                       __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Example 505.           

                                      TABLE 38                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                           Microwave                                                                     discharge                                                                     electric         Substrate                                                                            Layer                                        Gas used and                                                                           power       Pressure                                                                           temperature                                                                          thickness                             Layer name                                                                           flow (sccm)                                                                            (mW/cm.sup.3)                                                                       Bias  (mTorr)                                                                            (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          First n-                                                                             Si.sub.2 H.sub.6                                                                   1   RF 80       1500 370    20                             conditions                                                                           type layer                                                                           H.sub.2                                                                            50  (mW/cm.sup.2)                                          of layer      PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to                                                                   1%)                                                                    First i-                                                                             SiH.sub.4                                                                              Microwave                                                                           RF 350                                                                               10  350    300                                   type layer                                                                           See FIG. 35                                                                            170   (mW/cm.sup.3)                                           by     H.sub.2  (mW/cm.sup.3)                                                                       DC OV                                                   microwave                                                                            GeH.sub.4                                                              plasma CVD                                                                           See FIG. 35                                                                   BF.sub.3 /H.sub.2                                                                  0.3                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                             First i-                                                                             SiH4 8   RF 120       500 350    10                                    type layer                                                                           H2   100 (mW/cm.sup.2)                                                 by RF  BF.sub.3 /H.sub.2                                                                  0.5                                                               plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                             First p-                                                                             SiH4 0.05                                                                              RF 1.5      2000 250    10                                    type layer                                                                           H2   100 (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to                                                                   1%)                                                             __________________________________________________________________________    Fabrication                                                                          Second n-                                                                            Si.sub.2 H.sub.6                                                                   1   RF 80       1500 300    10                             conditions                                                                           type layer                                                                           H.sub.2                                                                            50  (mW/cm.sup.2)                                          of layer      PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to                                                                   1%)                                                                    Second i-                                                                            SiH.sub.4                                                                          200 Microwave                                                                           RF 250                                                                                5  300    150                                   type layer                                                                           H.sub.2                                                                            700 130   (mW/cm.sup.3)                                                           (mW/cm.sup.3)                                                                       DC OV                                                   Second p-                                                                            SiH4 0.05                                                                              RF 1.5      2000 200     5                                    type layer                                                                           H2   100 (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to                                                                   1%)                                                             __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 39                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                           Microwave                                                                     discharge                                                                     electric         Substrate                                                                            Layer                                        Gas used and                                                                           power       Pressure                                                                           temperature                                                                          thickness                             Layer name                                                                           flow (sccm)                                                                            (mW/cm.sup.3)                                                                       Bias  (mTorr)                                                                            (°C.)                                                                         (nm)                           __________________________________________________________________________    Fabrication                                                                          First n-                                                                             Si.sub.2 H.sub.4                                                                   50  130   DC    10   350    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    First i-                                                                             SiH.sub.4                                                                              170   RF 350                                                                              10   350    250                                   type layer                                                                           See FIG. 36A   (mW/cm.sup.3)                                           by     H.sub.2                                                                            500       DC OV                                                   microwave                                                                            GeH.sub.4                                                              plasma CVD                                                                           See FIG. 36A                                                                  BF.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.3                                                                      (2000 ppm)                                                             First i-                                                                             SiH4 8   RF 120      500  350    10                                    type layer                                                                           H2   100 (mW/cm.sup.2)                                                 by RF  BF.sub.3 /H.sub.2                                                                  0.3                                                               plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                             First p-                                                                             SiH4 10  250         25   350    10                                    type layer                                                                           H2   700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to                                                                   1%)                                                             __________________________________________________________________________    Fabrication                                                                          Second n-                                                                            SiH.sub.4                                                                          50  130   DC    10   350    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    Second i-                                                                            SiH.sub.4                                                                              210   RF 280                                                                              10   350    200                                   type layer                                                                           See FIG. 36B   (mW/cm.sup.3)                                           by     H.sub.2                                                                            500       DC OV                                                   microwave                                                                            GeH.sub.4                                                              plasma CVD                                                                           See FIG. 36B                                                                  BF.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.1                                                                      (2000 ppm)                                                             Second i-                                                                            SiH4 8   RF 120      500  350    200                                   type layer                                                                           H2   100 (W/cm.sup.2)                                                  by RF  BF.sub.3 /H.sub.2                                                                  1                                                                 plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                             Second i-                                                                            SiH4 8   RF 120      500  350    10                                    type layer                                                                           H2   100 (mW/cm.sup.2)                                                 by RF  BF.sub.3 /H.sub.2                                                                  1                                                                 plasma CVD                                                                           (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                             Second p-                                                                            SiH.sub.4                                                                          10  250         25   350    10                                    type layer                                                                           H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted by                                                                   1%)                                                             __________________________________________________________________________    Fabrication                                                                          Third n-                                                                             SiH.sub.4                                                                          50  130   DC    10   300    10                             conditions                                                                           type layer                                                                           PH.sub.3 /H.sub.2                                                                  200       50V                                              of layer      (diluted to                                                                   1%)                                                                    Third i-                                                                             SiH.sub.4                                                                          200 150   RF 300                                                                               5   300    100                                   type layer                                                                           H.sub.2                                                                            700       (mW/cm.sup.3)                                                                 DC OV                                                   Third p-                                                                             SiH4 10  250         25   250    5                                     type layer                                                                           H2   700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to                                                                   1%)                                                             __________________________________________________________________________    Transparent                                                                          ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                  electrode                                                                     Collector                                                                            Aluminum (Al) thin film 2 μm                                        electrode                                                                     __________________________________________________________________________

                                      TABLE 40                                    __________________________________________________________________________                              Low    Durability                                          Pressure           illuminance                                                                          characteristic                                      within             characteristic                                                                       Decrease in                                         deposition                                                                          Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       chamber                                                                             Open-circuit conversion                                                                           conversion                                   Element No.                                                                          (mTorr)                                                                             voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                   __________________________________________________________________________    Example 64-1                                                                         0.5   1.02   1.02  1.06   1.06                                         Example 64-2                                                                          1    1.02   1.02  1.06   1.06                                         Example 64-3                                                                          2    1.02   1.03  1.07   1.06                                         Example 64-4                                                                          5    1.04   1.04  1.07   1.08                                         Example 64-5                                                                         10    1.03   1.03  1.07   1.07                                         Example 64-6                                                                         20    1.04   1.02  1.06   1.07                                         Example 64-7                                                                         50    1.02   1.02  1.06   1.07                                         Comparative                                                                          100   1.00   1.00  1.00   1.00                                         Example 14-1                                                                  __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 141

                                      TABLE 41                                    __________________________________________________________________________                               Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                         Microwave                                                                           Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       power Open-circuit conversion                                                                           conversion                                  Element No.                                                                           (W/cm.sup.3)                                                                        voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Example 64-8                                                                          0.1   1.03   1.02  1.07   1.06                                        Example 64-9                                                                          0.2   1.02   1.03  1.08   1.09                                        Example 64-10                                                                         0.3   1.02   1.03  1.07   1.06                                        Comparative                                                                           0.4   1.00   1.01  1.01   1.02                                        Example 14-2                                                                  Comparative                                                                           0.5   1.00   1.00  1.00   1.00                                        Example 14-3                                                                  __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 143

                                      TABLE 42                                    __________________________________________________________________________                               Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                               Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       RF bias                                                                             Open-circuit conversion                                                                           conversion                                  Element No.                                                                           (mW/cm.sup.3)                                                                       voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Comparative                                                                           150   1.00   1.00  1.00   1.00                                        Example 14-4                                                                  Example 64-11                                                                         200   1.02   1.02  1.05   1.06                                        Example 64-12                                                                         250   1.03   1.03  1.07   1.08                                        Example 64-13                                                                         300   1.02   1.02  1.06   1.07                                        Example 64-14                                                                         350   1.02   1.02  1.06   1.06                                        __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 144

                                      TABLE 42                                    __________________________________________________________________________                               Low    Durability                                                             illuminance                                                                          characteristic                                                         characteristic                                                                       Decrease in                                               Initial characteristics                                                                    Photoelectric                                                                        photoelectric                                       RF bias                                                                             Open-circuit conversion                                                                           conversion                                  Element No.                                                                           (mW/cm.sup.3)                                                                       voltage                                                                              Fill factor                                                                         efficiency                                                                           efficiency                                  __________________________________________________________________________    Comparative                                                                           150   1.00   1.00  1.00   1.00                                        Example 14-4                                                                  Example 64-11                                                                         200   1.02   1.02  1.05   1.06                                        Example 64-12                                                                         250   1.03   1.03  1.07   1.08                                        Example 64-13                                                                         300   1.02   1.02  1.06   1.07                                        Example 64-14                                                                         350   1.02   1.02  1.06   1.06                                        __________________________________________________________________________     Note)                                                                         The initial characteristics, low illuminance characteristic and durabilit     are relative values with reference to Element No. Comparative Example 144

                                      TABLE 44                                    __________________________________________________________________________                                    Low     Durability                                     Layer                  illuminance                                                                           characteristic                                 thickness of           characteristic                                                                        Decrease in                                    i-type layer                                                                          Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                  by RF plasma                                                                          Open-circuit   conversion                                                                            conversion                            Element No.                                                                            CVD (nm)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Comparative                                                                            0       1.00    1.00   1.00    1.00                                  Example 14-7                                                                  Example 64-21                                                                          1       1.02    1.01   1.05    1.05                                  Example 64-22                                                                          3       1.03    1.02   1.06    1.06                                  Example 64-5                                                                           10      1.02    1.03   1.06    1.07                                  Example 64-23                                                                          30      1.02    1.02   1.04    1.05                                  Comparative                                                                            50      1.01    1.00   1.01    1.02                                  Example 14-8                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 147.                                                             

                                      TABLE 45                                    __________________________________________________________________________                     Value of                       Durability                                     half-width             Low     Characteristic                                 at a peak              Illuminance                                                                           Decrease in                            RF discharge                                                                          of 2000 cm.sup.-1                                                                     Initial Characteristics                                                                      Photoelectric                                                                         photoelectric                          power   divided by                                                                            Open-circuit   conversion                                                                            conversion                    Element No.                                                                            (mW/cm.sup.2)                                                                         peak height                                                                           voltage Fill factor                                                                          efficency                                                                             efficiency                    __________________________________________________________________________    Example 64-24                                                                          90      1.31    1.03    1.02   1.06    1.05                          Example 64-5                                                                           120     1.16    1.02    1.03   1.06    1.06                          Example 64-25                                                                          150     1.07    1.01    1.03   1.04    1.05                          Example 64-26                                                                          180     0.95    1.00    1.01   1.01    1.02                          Example 64-27                                                                          210     0.88    1.00    1.00   1.00    1.00                          __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 6427.                                                            

                                      TABLE 46                                    __________________________________________________________________________                                      Low     Durability                                  Layer                     illuminance                                                                           characteristic                              thickness of              characteristic                                                                        Decrease in                                 the region at                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               maximum bandgap                                                                          Open-circuit   conversion                                                                            conversion                          Element No.                                                                           (nm)       voltage Fill factor                                                                          efficiency                                                                            efficiency                          __________________________________________________________________________    Example 65-1                                                                          1          1.02    1.02   1.04    1.04                                Example 65-2                                                                          2          1.02    1.03   1.05    1.04                                Example 65-3                                                                          3          1.02    1.03   1.06    1.05                                Example 65-4                                                                          5          1.02    1.03   1.07    1.07                                Example 65-5                                                                          10         1.03    1.02   1.07    1.07                                Example 65-6                                                                          20         1.03    1.02   1.05    1.06                                Example 65-7                                                                          30         1.02    1.01   1.05    1.06                                Example 65-8                                                                          50         1.00    1.00   1.00    1.00                                __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 658.

                                      TABLE 47                                    __________________________________________________________________________            Distance                Low     Durability                                    between mixing          illuminance                                                                           characteristic                                point of gases          characteristic                                                                        Decrease in                                   and deposition                                                                         Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                 chamber  Open-circuit   conversion                                                                            conversion                            Element No.                                                                           (m)      voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Example 70-1                                                                          1        1.03    1.03   1.05    1.07                                  Example 70-2                                                                          2        1.02    1.04   1.07    1.06                                  Example 70-3                                                                          3        1.02    1.03   1.06    1.06                                  Example 70-4                                                                          5        1.02    1.03   1.04    1.06                                  Example 70-5                                                                          8        1.00    1.00   1.00    1.00                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 705.

                                      TABLE 48                                    __________________________________________________________________________                                    Low     Durability                                                            illuminance                                                                           characteristic                                Layer                   characteristic                                                                        Decrease in                                   thickness of                                                                           Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                 doping layer A                                                                         Open-circuit   conversion                                                                            conversion                            Element No.                                                                           (nm)     voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Example 76-1                                                                          0.01     1.02    1.02   1.05    1.06                                  Example 76-2                                                                          0.03     1.02    1.03   1.06    1.06                                  Example 76-3                                                                          0.1      1.03    1.03   1.07    1.07                                  Example 64-5                                                                          0.3      1.03    1.02   1.06    1.05                                  Example 76-4                                                                          1        1.02    1.02   1.05    1.04                                  Example 76-5                                                                          3        1.00    1.00   1.00    1.00                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 765.

                                      TABLE 49                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                             Microwave                                                                     discharge              Substrate                                                                             Layer                                  Gas used and                                                                          electric power  Pressure                                                                             temperature                                                                           thickness                     Layer name                                                                             flow (sccm)                                                                           (mW/cm.sup.3)                                                                          Bias   (mTorr)                                                                              (°C.)                                                                          (nm)                  __________________________________________________________________________    Fabrication                                                                           n-type layer                                                                           SiH.sub.4                                                                          50 130      DC 50 V                                                                              10     350     10                    conditions       PH.sub.3 /H.sub.2                                                                  200                                                     of layer         (diluted to 1%)                                                      i-type layer                                                                           SiH.sub.4                                                                          8  RF 120          500    350     10                            by RF    H.sub.2                                                                            100                                                                              (mW/cm.sup.3)                                                plasma CVD                                                                    i-type layer                                                                           SiH.sub.4                                                                             170      RF 350 See    350     300                           by microwave                                                                           See FIG. 14      (mW/cm.sup.3)                                                                        Table 2                                      plasma CVD                                                                             H.sub.2                                                                            500         DC 0 V                                                       GeH.sub.4                                                                     See FIG. 14                                                                   BF.sub.3 /H.sub.2 1                                                           (2000 ppm)                                                           p-type layer                                                                           SiH4 10 250             25     300     10                                     H2   700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                      __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

                                      TABLE 50                                    __________________________________________________________________________                                  Low     Durability                                      Pressure              illuminance                                                                           characteristic                                  within                characteristic                                                                        Decrease in                                     deposition                                                                           Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   chamber                                                                              Open-circuit   conversion                                                                            conversion                              Element No.                                                                           (mTorr)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                              __________________________________________________________________________    Example 87-1                                                                          0.5    1.02    1.02   1.06    1.06                                    Example 87-2                                                                          1      1.02    1.02   1.06    1.05                                    Example 87-3                                                                          2      1.02    1.02   1.08    1.06                                    Example 87-4                                                                          5      1.03    1.03   1.07    1.09                                    Example 87-5                                                                          10     1.04    1.02   1.05    1.08                                    Example 87-6                                                                          20     1.03    1.02   1.05    1.07                                    Example 87-7                                                                          50     1.03    1.02   1.04    1.06                                    Comparative                                                                           100    1.00    1.00   1.00    1.00                                    Example 87-1                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 871.                                                             

                  TABLE 51                                                        ______________________________________                                                          Decomposition efficiency of                                        Gas flow   source gas at each microwave                                       rate (sccm)                                                                              electric power (W/cm.sup.3) (%)                             Sample No.                                                                             SiH.sub.4                                                                             GeH.sub.4                                                                              0.1  0.2 0.3  0.4  0.5                              ______________________________________                                        Example 87-1                                                                           200     1        24   45  68   93   100                              Example 87-2                                                                           170     20       25   48  73   97   100                              Example 87-3                                                                           140     40       27   51  76   99   100                              Example 87-4                                                                           110     60       28   53  81   100  100                              Example 87-5                                                                           80      80       31   58  88   100  100                              ______________________________________                                    

                                      TABLE 52                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                     Microwave                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   power  Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (W/cm.sup.3)                                                                         voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Example 87-8                                                                           0.1    1.03    1.02   1.06    1.08                                   Example 87-9                                                                           0.2    1.03    1.03   1.07    1.08                                   Example 87-10                                                                          0.3    1.01    1.02   1.07    1.07                                   Comparative                                                                            0.4    1.00    1.01   1.01    1.01                                   Example 87-2                                                                  Comparative                                                                            0.5    1.00    1.00   1.00    1.00                                   Example 87-3                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 873.                                                             

                                      TABLE 53                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   RF bias                                                                              Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (mW/cm.sup.3)                                                                        voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Comparative                                                                            150    1.00    1.00   1.00    1.00                                   Example 87-4                                                                  Example 87-11                                                                          200    1.02    1.01   1.04    1.06                                   Example 87-12                                                                          250    1.03    1.03   1.06    1.07                                   Example 87-13                                                                          300    1.04    1.03   1.06    1.07                                   Example 87-14                                                                          350    1.02    1.02   1.07    1.06                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 874.                                                             

                  TABLE 54                                                        ______________________________________                                                 Gas flow             Composition                                              rate (sccm)                                                                              Bandgap   ratio                                           Sample No. SiH.sub.4                                                                             GeH.sub.4                                                                              (eV)    Si    Ge                                  ______________________________________                                        Example 87-6                                                                             200      1       1.71    100   1                                   Example 87-7                                                                             170     20       1.60    8.7   1                                   Example 87-8                                                                             140     40       1.52    3.3   1                                   Example 87-9                                                                             110     60       1.45    1.9   1                                   Example 87-10                                                                             80     80       1.38    1.1   1                                   Example 87-11                                                                            --      --       1.69    --    --                                  ______________________________________                                    

                                      TABLE 55                                    __________________________________________________________________________                                                           Durability                                                            Low     Characteristic                                                        Illuminance                                                                           Decrease in                     Flow rate              Initial Characteristics                                                                      Photoelectric                                                                         photoelectric                   of SiH.sub.4 gas                                                                     RF power                                                                             Deposition rate                                                                        Open-circuit   conversion                                                                            conversion             Element No.                                                                            (sccm) (mW/cm.sup.2)                                                                        (nm/sec) voltage Fill factor                                                                          efficency                                                                             efficiency             __________________________________________________________________________    Example 87-15                                                                          1      15     0.05     1.02    1.04   1.07    1.07                   (87-12)                                                                       Example 87-16                                                                          2      30     0.1      1.03    1.03   1.08    1.06                   (87-13)                                                                       Example 87-17                                                                          10     150    0.5      1.03    1.04   1.07    1.07                   (87-14)                                                                       Example 87-18                                                                          20     300    1.1      1.02    1.03   1.07    1.07                   (87-15)                                                                       Example 87-19                                                                          40     500    2.0      1.01    1.03   1.06    1.05                   (87-16)                                                                       Comparative                                                                            60     1000   2.8      1.00    1.00   1.00    1.00                   Example 87-6                                                                  (87-17)                                                                       __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 876.                                                             

                                      TABLE 56                                    __________________________________________________________________________                                    Low     Durability                                     Layer                  illuminance                                                                           characteristic                                 thickness of           characteristic                                                                        Decrease in                                    i-type layer                                                                          Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                  by RF plasma                                                                          Open-circuit   conversion                                                                            conversion                            Element No.                                                                            CVD (nm)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Comparative                                                                            0       1.00    1.00   1.00    1.00                                  Example 87-7                                                                  Example 87-20                                                                          1       1.02    1.01   1.03    1.04                                  Example 87-21                                                                          3       1.03    1.02   1.04    1.06                                  Example 87-5                                                                           10      1.03    1.03   1.07    1.08                                  Example 87-22                                                                          30      1.03    1.02   1.05    1.07                                  Comparative                                                                            50      1.01    1.00   1.01    1.02                                  Example 87-8                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 877.                                                             

                                      TABLE 57                                    __________________________________________________________________________                     Value of                       Durability                                     half-width             Low     Characteristic                                 at a peak              Illuminance                                                                           Decrease in                            RF discharge                                                                          of 2000 cm.sup.-1                                                                     Initial Characteristics                                                                      Photoelectric                                                                         photoelectric                 Element No.                                                                            power   divided by                                                                            Open-circuit   conversion                                                                            conversion                    (Sample No.)                                                                           (mW/cm.sup.2)                                                                         peak height                                                                           voltage Fill factor                                                                          efficency                                                                             efficiency                    __________________________________________________________________________    Example 87-23                                                                          90      1.31    1.02    1.03   1.04    1.06                          (87-18)                                                                       Example 87-5                                                                           120     1.16    1.02    1.02   1.04    1.06                          (87-19)                                                                       Example 87-24                                                                          150     1.07    1.01    1.02   1.05    1.05                          (87-20)                                                                       Example 87-25                                                                          180     0.95    1.00    1.01   1.02    1.01                          (87-21)                                                                       Example 87-26                                                                          210     0.88    1.00    1.00   1.00    1.00                          (87-22)                                                                       (87-23)          1.0                                                          __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 8726     The value of halfwidth divided by height is relative value with reference     to Sample No. 8723.                                                      

                                      TABLE 58                                    __________________________________________________________________________                                      Low     Durability                                  Layer                     illuminance                                                                           characteristic                              thickness of              characteristic                                                                        Decrease in                                 the region at                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               maximum bandgap                                                                          Open-circuit   conversion                                                                            conversion                          Element No.                                                                           (nm)       voltage Fill factor                                                                          efficiency                                                                            efficiency                          __________________________________________________________________________    Example 88-1                                                                          1          1.02    1.02   1.03    1.03                                Example 88-2                                                                          2          1.02    1.03   1.05    1.04                                Example 88-3                                                                          3          1.03    1.04   1.06    1.07                                Example 88-4                                                                          5          1.04    1.03   1.06    1.06                                Example 88-5                                                                          10         1.03    1.03   1.05    1.06                                Example 88-6                                                                          20         1.03    1.02   1.04    1.05                                Example 88-7                                                                          30         1.01    1.02   1.04    1.04                                Example 88-8                                                                          50         1.00    1.00   1.00    1.00                                __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 888.

                                      TABLE 59                                    __________________________________________________________________________            Distance                Low     Durability                                    between mixing          illuminance                                                                           characteristic                                point of gases          characteristic                                                                        Decrease in                                   and deposition                                                                         Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                 chamber  Open-circuit   conversion                                                                            conversion                            Element No.                                                                           (m)      voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Example 93-1                                                                          1        1.03    1.04   1.05    1.07                                  Example 93-2                                                                          2        1.03    1.03   1.05    1.06                                  Example 93-3                                                                          3        1.02    1.03   1.04    1.04                                  Example 93-4                                                                          5        1.01    1.02   1.04    1.03                                  Example 93-5                                                                          8        1.00    1.00   1.00    1.00                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 935.

                                      TABLE 60                                    __________________________________________________________________________                     RF discharge   Substrate                                                                             Layer                                         Gas used and                                                                           electric power                                                                         Pressure                                                                            temperature                                                                           thickness                                     flow (sccm)                                                                            (W/cm.sup.2)                                                                           (Torr)                                                                              (°C.)                                                                          (nm)                                  __________________________________________________________________________    Fabrication                                                                           SiH.sub.4                                                                          8   0.12     500   300     10                                    conditions                                                                            H.sub.2                                                                            100                                                              of i-type                                                                             BF.sub.3 /H.sub.2                                                                  1                                                                layer by RF                                                                           (diluted to                                                           plasma CVD                                                                            2000 ppm)                                                                     PH.sub.3 /H.sub.2                                                                  0.06                                                                     (diluted to                                                                   2000 ppm)                                                             __________________________________________________________________________

                                      TABLE 61                                    __________________________________________________________________________    Substrate       SUS430BA 50 mm square 1 mm thick                              Reflecting layer                                                                              Silver (Ag) thin film 100 nm                                  Reflection multiplying layer                                                                  Zinc Oxide (ZnO) thin film 1 μm                            __________________________________________________________________________                            RF discharge   Substrate                                                                             Layer                                          Gas used and                                                                          electric power                                                                         Pressure                                                                            temperature                                                                           thickness                              Layer name                                                                            flow (sccm)                                                                           (W/cm.sup.3)                                                                           (mTorr)                                                                             (°C.)                                                                          (nm)                           __________________________________________________________________________    Fabrication                                                                           n-type layer                                                                          Si.sub.2 H.sub.6                                                                   3  0.12     1     350     10                             conditions      PH.sub.3 /H.sub.2                                                                  5                                                        of layer        (diluted to 1%)                                                               H.sub.2                                                                            50                                                               i-type layer                                                                          Same as Element No. Example 87-5                                      p-type layer                                                                          SiH4 0.5                                                                              2        1     200     5                                              H2   100                                                                      BF.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                               __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

                                      TABLE 62                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                              Discharge             Substrate                                                                             Layer                                  Gas used and                                                                           electric       Pressure                                                                             temperature                                                                           thickness                     Layer name                                                                             flow (sccm)                                                                            power   Bias   (mTorr)                                                                              (°C.)                                                                          (nm)                  __________________________________________________________________________    Fabrication                                                                           First n-type                                                                           Si.sub.2 H.sub.6                                                                   1   RF 80          1500   370     20                    conditions                                                                            layer    H.sub.2                                                                            50  (mW/cm.sup.2)                                       of layer         PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                      First i-type                                                                           SiH4 8   RF 120         500    350     20                            layer 1 by RF                                                                          H2   100 (mW/cm.sup.2)                                               plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.02                                                                     (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.04                                                                     (2000 ppm)                                                           First i-type                                                                           SiH.sub.4                                                                              Microwave                                                                             RF 350 10     350     300                           layer by See FIG. 38                                                                            170     (mW/cm.sup.3)                                       microwave                                                                              H.sub.2                                                                            500 (mW/cm.sup.3)                                                                         DC 0 V                                              plasma CVD                                                                             GeH.sub.4                                                                     See FIG. 38                                                                   H.sub.2                                                                            700                                                             First i-type                                                                           SiH4 8   RF 120         500    350     10                            layer 2 by RF                                                                          H2   100 (mW/cm.sup.2)                                               plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  2                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                           First p-type                                                                           SiH4 0.05                                                                              RF 1.5         2000   250     10                            layer    H2   100 (W/cm.sub.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to 1%)                                                      Second n-type                                                                          Si.sub.2 H.sub.6                                                                   1   RF 80          1500   300     10                            layer    H.sub.2                                                                            50  (mW/cm.sup.2)                                                        PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                      Second i-type                                                                          SiH.sub.4                                                                          200 Microwave                                                                             RF 250 5      300     150                           layer    H.sub.2                                                                            700 130     (mW/cm.sup.3)                                                         (mW/cm.sup.3)                                                                         DC 0 V                                              Second p-type                                                                          SiH4 0.05                                                                              RF 1.5         2000   200     5                             layer    H2   100 (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to 1%)                                              __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

                                      TABLE 63                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                              Microwave                                                                     discharge             Substrate                                                                             Layer                                  Gas used and                                                                           electric power  Pressure                                                                            temperature                                                                           thickness                     Layer name                                                                             flow (sccm)                                                                            (mW/cm.sup.3)                                                                          Bias   (mTorr)                                                                             (°C.)                                                                          (nm)                  __________________________________________________________________________    Fabrication                                                                           First n-type                                                                           SiH.sub.4                                                                          50  130      DC     10    350     10                    conditions                                                                            layer    PH.sub.3 /H.sub.2                                                                  200          50 V                                       of layer         (diluted to 1%)                                                      First i-type                                                                           SiH.sub.4                                                                          8   RF 120          500   350     10                            layer 1 by                                                                             H.sub.2                                                                            100 (mW/cm.sup.2)                                               RF Plasma                                                                              BF.sub.3 /H.sub.2                                                                  0.05                                                            CVD plasma                                                                             (2000 ppm)                                                           CVD      PH.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                           First i-type                                                                           SiH.sub.4                                                                              170      RF 120 10    350     250                           layer by FIG. 39           (mW/cm.sup.3)                                      Microwave                                                                              H.sub.2                                                                            500          DC 0 V                                             plasma CVD                                                                             GeH.sub.4                                                                     See FIG. 39                                                          First i-type                                                                           SiH4 8   RF 120          500   35      10                            layer 2 by                                                                             H2   100 (mW/cm.sup.2)                                               RF plasma                                                                              BF.sub.3 /H.sub.2                                                                  0.05                                                            CVD      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.01                                                                     (2000 ppm)                                                           First p-type                                                                           SiH4 10  250             25    350     10                            layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to 1%)                                                      Second n-type                                                                          SiH.sub.4                                                                          50  130      DC     10    350     10                            layer    PH.sub.3 /H.sub.2                                                                  200          50 V                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  3                                                                        (2000 ppm)                                                           Second i-type                                                                          SiH.sub.4                                                                          8   RF 120          500   350     10                            layer 1 by RF                                                                          H.sub.2                                                                            100 (mW/cm.sup.2)                                               plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.1                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  3                                                                        (2000 ppm)                                                           Second i-type                                                                          SiH.sub.4                                                                              210      RF 280 10    350     200                           layer by See FIG. 40       (mW/cm.sup.3)                                      microwave                                                                              H.sub.2                                                                            500          DC 0 V                                             plasma CVD                                                                             GeH.sub.4                                                                     See FIG. 40                                                          Second i-type                                                                          SiH.sub.4                                                                          8   RF 120          500   350     10                            layer 2 by RF                                                                          H.sub.2                                                                            100 (mW/cm.sup.2)                                               plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                           Second p-type                                                                          SiH.sub.4                                                                          10  250             25    350     10                            layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted by 1%)                                                      Third n-type                                                                           SiH.sub.4                                                                          50  130      DC 50 V                                                                              10    300     10                            layer    PH.sub.3 /H.sub.2                                                                  200                                                                      (diluted to 1%)                                                      Third i-type                                                                           SiH.sub.4                                                                          200 150      RF 300 5     300     100                           layer    H.sub.2                                                                            700          (mW/cm.sup.3)                                      Third p-type                                                                           SiH.sub.4                                                                          10  250             25    300     5                             layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to 1%)                                              __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

                                      TABLE 64                                    __________________________________________________________________________                                       Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                 Pressure within                                                                          Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               deposition chamber                                                                       Open-circuit   conversion                                                                            conversion                         Element No.                                                                            (mTorr)    voltage Fill factor                                                                          efficiency                                                                            efficiency                         __________________________________________________________________________    Example 107-1                                                                          0.5        1.02    1.02   1.06    1.06                               Example 107-2                                                                          1          1.02    1.02   1.06    1.06                               Example 107-3                                                                          2          1.03    1.03   1.07    1.06                               Example 107-4                                                                          5          1.03    1.03   1.07    1.08                               Example 107-5                                                                          10         1.04    1.02   1.07    1.08                               Example 107-6                                                                          20         1.03    1.02   1.06    1.07                               Example 107-7                                                                          50         1.03    1.01   1.06    1.07                               Comparative                                                                            100        1.00    1.00   1.00    1.00                               Example 93-1                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 931.                                                             

                                      TABLE 65                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                     Microwave                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   power  Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (W/cm.sup.3)                                                                         voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Example 107-8                                                                          0.1    1.03    1.02   1.07    1.06                                   Example 107-9                                                                          0.2    1.02    1.02   1.09    1.09                                   Example 107-10                                                                         0.3    1.02    1.02   1.06    1.07                                   Comparative                                                                            0.4    1.00    1.01   1.01    1.02                                   Example 93-2                                                                  Comparative                                                                            0.5    1.00    1.00   1.00    1.00                                   Example 93-3                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 933.                                                             

                                      TABLE 66                                    __________________________________________________________________________                                   Low     Durability                                                            illuminance                                                                           characteristic                                                        characteristic                                                                        Decrease in                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                   RF bias                                                                              Open-circuit   conversion                                                                            conversion                             Element No.                                                                            (mW/cm.sup.3)                                                                        voltage Fill factor                                                                          efficiency                                                                            efficiency                             __________________________________________________________________________    Comparative                                                                            150    1.00    1.00   1.00    1.00                                   Example 93-4                                                                  Example 107-11                                                                         200    1.02    1.02   1.05    1.06                                   Example 107-12                                                                         250    1.02    1.03   1.06    1.08                                   Example 107-13                                                                         300    1.03    1.03   1.06    1.07                                   Example 107-14                                                                         350    1.02    1.02   1.07    1.05                                   __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 934.                                                             

                                      TABLE 67                                    __________________________________________________________________________                                                          Durability                                                            Low     Characterics                                                          Illuminance                                                                           Decrease in                      Flow rate     Deposition                                                                            Initial Characteristics                                                                      Photoelectric                                                                         photoelectric                    of SiH.sub.4 gas                                                                     RF power                                                                             rate    Open-circuit   conversion                                                                            conversion              Element No.                                                                            (sccm) (mW/cm.sup.2)                                                                        (nm/sec)                                                                              voltage Fill factor                                                                          efficency                                                                             efficiency              __________________________________________________________________________    Example 107-16                                                                         1      15     0.05    1.03    1.03   1.08    1.07                    Example 107-17                                                                         2      30     0.1     1.04    1.03   1.07    1.07                    Example 107-18                                                                         10     150    0.5     1.04    1.02   1.07    1.08                    Example 107-19                                                                         20     300    1.1     1.03    1.02   1.07    1.07                    Example 107-20                                                                         40     500    2.0     1.03    1.02   1.06    1.06                    Comparative                                                                            60     1000   2.8     1.00    1.00   1.00    1.00                    Example 93-6                                                                  __________________________________________________________________________

                                      TABLE 68                                    __________________________________________________________________________                                    Low     Durability                                     Layer                  illuminance                                                                           characteristic                                 thickness of           characteristic                                                                        Decrease in                                    i-type layer                                                                          Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                  by RF plasma                                                                          Open-circuit   conversion                                                                            conversion                            Element No.                                                                            CVD (nm)                                                                              voltage Fill factor                                                                          efficiency                                                                            efficiency                            __________________________________________________________________________    Comparative                                                                            0       1.00    1.00   1.00    1.00                                  Example 93-7                                                                  Example 107-21                                                                         1       1.02    1.02   1.03    1.05                                  Example 107-22                                                                         3       1.03    1.02   1.05    1.07                                  Example 107-5                                                                          10      1.03    1.03   1.06    1.07                                  Example 107-23                                                                         30      1.02    1.02   1.06    1.05                                  Comparative                                                                            50      1.01    1.00   1.02    1.01                                  Example 93-8                                                                  __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Comparative      Example 937.                                                             

                                      TABLE 69                                    __________________________________________________________________________                     Value of                      Durability                                      half-width            Low     Characterics                                    at a peak of          Illuminance                                                                           Decrease in                             RF discharge                                                                          2000 cm.sup.-1                                                                       Initial Characteristics                                                                      Photoelectric                                                                         photoelectric                           power   divided by                                                                           Open-circuit   conversion                                                                            conversion                     Element No.                                                                            (mW/cm.sup.2)                                                                         peak height                                                                          voltage Fill factor                                                                          efficency                                                                             efficiency                     __________________________________________________________________________    Comparative                                                                            90      1.31   1.03    1.02   1.04    1.05                           Example 107-24                                                                Example 107-5                                                                          120     1.16   1.02    1.03   1.05    1.06                           Example 107-25                                                                         150     1.07   1.01    1.01   1.04    1.05                           Example 107-26                                                                         180     0.95   1.00    1.01   1.01    1.02                           Example 107-27                                                                         210     0.88   1.00    1.00   1.00    1.00                           __________________________________________________________________________

                                      TABLE 70                                    __________________________________________________________________________                                       Low     Durability                                  Layer                     illuminance                                                                           characteristic                              thickness of              characteristic                                                                        Decrease in                                 the region at                                                                            Initial characteristics                                                                      Photoelectric                                                                         photoelectric                               maximum bandgap                                                                          Open-circuit   conversion                                                                            conversion                         Element No.                                                                            (nm)       voltage Fill factor                                                                          efficiency                                                                            efficiency                         __________________________________________________________________________    Example 108-1                                                                          1          1.01    1.02   1.04    1.03                               Example 108-2                                                                          2          1.02    1.03   1.05    1.04                               Example 108-3                                                                          3          1.02    1.03   1.05    1.06                               Example 108-4                                                                          5          1.03    1.02   1.05    1.07                               Example 108-5                                                                          10         1.04    1.02   1.06    1.06                               Example 108-6                                                                          20         1.04    1.02   1.05    1.06                               Example 108-7                                                                          30         1.02    1.02   1.04    1.05                               Example 108-8                                                                          50         1.00    1.00   1.00    1.00                               __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 1088

                                      TABLE 71                                    __________________________________________________________________________             Distance                Low     Durability                                    between mixing          illuminance                                                                           characteristic                                point of gases          characteristic                                                                        Decrease in                                   and deposition                                                                         Initial characteristics                                                                      Photoelectric                                                                         photoelectric                                 chamber  Open-circuit   conversion                                                                            conversion                           Element No.                                                                            (m)      voltage Fill factor                                                                          efficiency                                                                            efficiency                           __________________________________________________________________________    Example 113-1                                                                          1        1.03    1.03   1.06    1.07                                 Example 113-2                                                                          2        1.03    1.04   1.05    1.06                                 Example 113-3                                                                          3        1.02    1.03   1.04    1.06                                 Example 113-4                                                                          5        1.02    1.03   1.02    1.05                                 Example 113-5                                                                          8        1.00    1.00   1.00    1.00                                 __________________________________________________________________________     Note) The initial characteristics, low illuminance characteristic and         durability are relative values with reference to Element No. Example 1135

                                      TABLE 72                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc Oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                              Discharge             Substrate                                                                             Layer                                  Gas used and                                                                           electric       Pressure                                                                             temperature                                                                           thickness                     Layer name                                                                             flow (sccm)                                                                            power   Bias   (mTorr)                                                                              (°C.)                                                                          (nm)                  __________________________________________________________________________    Fabrication                                                                           First n-type                                                                           Si.sub.2 H.sub.4                                                                   1   RF 80          500    370     20                    conditions                                                                            layer    H.sub.2                                                                            50  (mW/cm.sup.2)                                       of layer         PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                      First i-type                                                                           SiH.sub.4                                                                          8   RF 120         500    350     20                            layer 1 by RF                                                                          H.sub.2                                                                            100 (mW/cm.sup.2)                                               Plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.03                                                                     (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                           First i-type                                                                           SiH.sub.4                                                                              Microwave                                                                             RF 120 10     350     300                           layer 2 by                                                                             See FIG. 38                                                                            170     (mW/cm.sup.3)                                       Microwave                                                                              H.sub.2                                                                            500 (mW/cm.sup.2)                                                                         DC 0 V                                              plasma CVD                                                                             GeH.sub.4                                                                     See FIG. 38                                                          First i-type                                                                           SiH4 8   RF 120         500    350     10                            layer by RF                                                                            H2   100 (mW/cm.sup.2)                                               plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  3                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                           First p-type                                                                           SiH4 0.05                                                                              RF 1.5         2000   250     10                            layer    H.sub.2                                                                            100 (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to 1%)                                                      Second n-type                                                                          Si.sub.2 H.sub.6                                                                   1   RF 80          1500   300     10                            layer    H.sub.2                                                                            50  (mW/cm.sup.2)                                                        PH.sub.3 /H.sub.2                                                                  1                                                                        (diluted to 1%)                                                      Second i-type                                                                          SiH.sub.4                                                                          200 Microwave                                                                             RF 250 5      300     150                           layer    H.sub.2                                                                            700 130     (mW/cm.sup.3)                                                         (mW/cm.sup.3)                                                                         DC 0 V                                              Second p-type                                                                          SiH4 0.05                                                                              RF 1.5         2000   200     5                             layer    H2   100 (W/cm.sup.2)                                                         BF.sub.3 /H.sub.2                                                                  5                                                                        (diluted to 1%)                                              __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

                                      TABLE 73                                    __________________________________________________________________________    Substrate        SUS430BA 50 mm square 1 mm thick                             Reflecting layer Silver (Ag) thin film 100 nm                                 Reflection multiplying layer                                                                   Zinc oxide (ZnO) thin film 1 μm                           __________________________________________________________________________                               Microwave                                                                     discharge             Substrate                                                                             Layer                                 gas used and                                                                            electric power  Pressure                                                                            temperature                                                                           thickness                    Layer name                                                                             flow (sccm)                                                                             (mW/cm.sup.3)                                                                          Bias   (mTorr)                                                                             (°C.)                                                                          (nm)                 __________________________________________________________________________    Fabrication                                                                           First n-type                                                                           SiH.sub.4                                                                          50   130      DC     10    350     10                   conditions                                                                            layer    PH.sub.3 /H.sub.2                                                                  200           50 V                                      of layer         (diluted to 1%)                                                      First i-type                                                                           SiH.sub.4                                                                          8    RF 120          500   350     10                           layer 1 by RF                                                                          H.sub.2                                                                            100  (mW/cm.sup.2)                                              plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.03                                                                     (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                           First i-type                                                                           SiH.sub.4 See FIG. 39                                                                   170      RF 350 10    350     250                          layer by H.sub.2                                                                            500           (mW/cm.sup.3)                                     microwave                                                                              GeH.sub.4 See FIG. 39                                                                            DC 0 V                                            plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.3                                                                      (2000 ppm)                                                           First i-type                                                                           SiH.sub.4                                                                          8    RF 120          500   350     10                           layer 2 by RF                                                                          H.sub.2                                                                            100  (mW/cm.sup.2)                                              plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.3                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                           First p-type                                                                           SiH.sub.4                                                                          10   250             25    350     10                           layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to 1%)                                                      Second n-type                                                                          SiH.sub.4                                                                          50   130      DC 50 V                                                                              10    350     10                           layer    PH.sub.3 /H.sub.2                                                                  200                                                                      (diluted to 1%)                                                      Second i-type                                                                          SiH.sub.4                                                                          8    RF 120          500   350     10                           layer 1 by RF                                                                          H.sub.2                                                                            100  (mW/cm.sup.2)                                              plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.1                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  2                                                                        (2000 ppm)                                                           Second i-type                                                                          SiH.sub.4 See FIG. 40                                                                   210      RF 280 10    350     200                          layer by H.sub.2                                                                            500           (mW/cm.sup.3)                                     microwave                                                                              GeH.sub.4 See FIG. 40                                                                            DC 0 V                                            plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  0.5                                                                      (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.1                                                                      (2000 ppm)                                                           Second i-type                                                                          SiH.sub.4                                                                          8    RF 120          500   350     10                           layer 2 by RF                                                                          H.sub.2                                                                            100  (mW/cm.sup.2)                                              plasma CVD                                                                             BF.sub.3 /H.sub.2                                                                  1                                                                        (2000 ppm)                                                                    PH.sub.3 /H.sub.2                                                                  0.05                                                                     (2000 ppm)                                                           Second p-type                                                                          SiH.sub.4                                                                          10   250             25    350     10                           layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted by 1%)                                                      Third n-type                                                                           SiH.sub.4                                                                          50   130      DC 50 V                                                                              10    300     10                           layer    PH.sub.3 /H.sub.2                                                                  200                                                                      (diluted to 1%)                                                      Third i-type                                                                           SiH.sub.4                                                                          200  150      RF 300 5     300     100                          layer    H.sub.2                                                                            700           (mW/cm.sup.3)                                                                 DC 0 V                                            Third p-type                                                                           SiH.sub.4                                                                          10   250             25    250     5                            layer    H.sub.2                                                                            700                                                                      BF.sub.3 /H.sub.2                                                                  30                                                                       (diluted to 1%)                                              __________________________________________________________________________    Transparent                                                                           ITO (In.sub.2 O.sub.3 + SnO.sub.2) thin film 70 μm                 electrode                                                                     Collector                                                                             Aluminum (Al) thin film 2 μm                                       electrode                                                                     __________________________________________________________________________

As described above, the present invention provides a photoelectricconversion element with improved photoelectric conversion efficiency inwhich the open-circuit voltage and the path length of holes are enhancedby preventing the recombination of photoexcited carriers. Also, thephotoelectric conversion element of the present invention has a superiorconversion efficiency when the illuminating light is weak. Thephotoelectric conversion element of the present invention is not easilydegraded in photoelectric conversion efficiency when annealed undervibrations for a long time period.

Furthermore, a power supply system utilizing the photoelectricconversion element of the present invention exhibits an excellentelectric power supply capability when the illuminating light is weak.

What is claimed is:
 1. A method for forming a non-monocrystallinesilicon semiconductor device with a pin junction comprising:forming afirst doped semiconductor layer of a first conductivity type disposed ona substrate; depositing a first intrinsic semiconductor layer on thefirst doped semiconductor layer by CVD employing RF energy; depositing asecond intrinsic semiconductor layer on the first intrinsic layer by CVDemploying microwave energy and RF energy simultaneously, while supplyinga semiconductor precursor gas including germanium and a semiconductorprecursor gas including silicon, wherein the content of saidsemiconductor precursor gas including germanium is greater than saidsemiconductor precursor gas including silicon in the layer thicknessdirection toward the p-layer side; and depositing a second dopedsemiconductor layer on said second intrinsic layer, said second dopedsemiconductor layer being of opposite conductivity type than said firstdoped semiconductor layer.
 2. The method according to claim 1, whereinsaid first intrinsic layer is formed up to a thickness of 30 nm at adeposition rate not greater than 2 nm/sec.
 3. The method according toclaim 1, wherein said second intrinsic layer is formed at a pressure notgreater than 50 m Torr.
 4. The method according to claim 1, includingincorporating a valence electron control agent in said intrinsic layers.5. The method according to claim 4, including varying the amount of saidincorporated valence electron control agent in the layer thicknessdirection.
 6. The method according to claim 1, including the stepsofforming a p-layer on the substrate as said first doped semiconductorlayer; depositing the first intrinsic layer on the p-layer by CVDemploying RF energy; depositing the second intrinsic layer on the firstintrinsic lay by CVD employing microwave energy and RF energysimultaneously, while supplying said semiconductor precursor gasincluding germanium and said semiconductor precursor gas includingsilicon, wherein the content of said semiconductor precursor gascontaining germanium is greater than said semiconductor precursor gasincluding silicon in the layer thickness direction toward the p-layerside; and depositing an n-layer on said second intrinsic layer as saidsecond doped semiconductor layer.
 7. The method of claim 1, includingthe steps offorming a p-layer on said substrate as said first dopedsemiconductor layer; depositing the second intrinsic layer on thep-layer by CVD employing microwave energy and RF energy simultaneously,while supplying said semiconductor precursor gas including germanium andsaid semiconductor precursor gas including silicon, wherein the contentof said semiconductor precursor gas containing germanium is greater thansaid semiconductor precursor gas including silicon in the layerthickness direction toward the p-layer side; depositing the firstintrinsic layer on the second intrinsic layer by CVD employing RFenergy; and depositing an n-layer as said second doped semiconductorlayer on the second intrinsic layer.
 8. The method according to any oneof claims 6 or 7, wherein the second intrinsic layer is formed at apressure not greater than 50 m Torr.
 9. The method according to any oneof claims 6 or 7, wherein the first intrinsic layer is formed up to athickness of 30 nm at a deposition rate not greater than 2 nm/sec. 10.The method according to any one of claims 6 or 7, includingincorporating a valence electron control agent in said intrinsic layers.11. The method according to claim 10 including varying the amount ofsaid valence electron control agent in the layer thickness direction.12. The method according to claim 1, including the step of forming athird intrinsic layer by CVD, including applying RF energy after formingthe second intrinsic layer.
 13. A method for forming anon-monocrystalline silicon semiconductor device with a pin junction inan apparatus having a plurality of deposition chambers arranged insequence comprising:(a) forming in a first deposition chamber a firstsemiconductor layer doped with a first impurity of a first conductivitytype disposed on a substrate; (b) depositing in a second depositionchamber a first intrinsic semiconductor layer on the first semiconductorlayer by CVD employing RF energy; (c) depositing in a third depositionchamber a second intrinsic semiconductor layer on the first intrinsicsemiconductor layer by CVD employing microwave energy and RF energysimultaneously in an atmosphere to which a starting gas includinggermanium and a starting gas including silicon are supplied; (d)depositing in a fourth deposition chamber a second semiconductor layerdoped with a second impurity of a second conductivity type opposite tothe first conductivity type on the second intrinsic semiconductor layerby CVD employing RF energy; and (e) transporting the substrate throughthe first, second, third, and fourth deposition chambers in sequencewithout exposing the substrate and the deposited layers thereon to theatmosphere when conducting steps (a) through (d).
 14. The methodaccording to claim 13, including supplying microwave energy to the thirdchamber in an amount smaller than that of the RF energy.
 15. The methodaccording to claim 13, including supplying the microwave energy and theRF energy to the third deposition chamber in an amount of 0.02-1 W/cm²and 0.04-2 W/cm² respectively.
 16. The method according to claim 13,including providing a fifth deposition chamber between the third and thefourth deposition chambers and depositing a third intrinsicsemiconductor layer by CVD employing RF energy.
 17. The method accordingto claim 16, including depositing a third intrinsic semiconductor layerin the fifth deposition chamber by CVD employing RF energy in anatmosphere to which a starting gas including germanium and a startinggas including silicon are supplied.
 18. The method according to claim17, including varying the concentration of germanium supplied by thestarting gas including germanium into the third deposition chamber withthe lapse of the deposition time during deposition of the secondintrinsic semiconductor layer.
 19. The method according to claim 13,wherein the first conductivity type is n-type and the secondconductivity type is p-type.